323 lines
18 KiB
JSON
323 lines
18 KiB
JSON
{
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"dataType": "CVE_RECORD",
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"dataVersion": "5.2",
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"cveMetadata": {
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"cveId": "CVE-2025-40026",
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"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"state": "PUBLISHED",
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"assignerShortName": "Linux",
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"dateReserved": "2025-04-16T07:20:57.152Z",
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"datePublished": "2025-10-28T09:32:33.075Z",
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"dateUpdated": "2026-10-15T22:02:36.361Z"
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},
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"containers": {
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"cna": {
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"providerMetadata": {
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"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"shortName": "Linux",
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"dateUpdated": "2026-08-05T12:07:08.793Z"
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},
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"descriptions": [
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{
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"lang": "en",
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: x86: Don't (re)check L1 intercepts when completing userspace I/O\n\nWhen completing emulation of instruction that generated a userspace exit\nfor I/O, don't recheck L1 intercepts as KVM has already finished that\nphase of instruction execution, i.e. has already committed to allowing L2\nto perform I/O. If L1 (or host userspace) modifies the I/O permission\nbitmaps during the exit to userspace, KVM will treat the access as being\nintercepted despite already having emulated the I/O access.\n\nPivot on EMULTYPE_NO_DECODE to detect that KVM is completing emulation.\nOf the three users of EMULTYPE_NO_DECODE, only complete_emulated_io() (the\nintended \"recipient\") can reach the code in question. gp_interception()'s\nuse is mutually exclusive with is_guest_mode(), and\ncomplete_emulated_insn_gp() unconditionally pairs EMULTYPE_NO_DECODE with\nEMULTYPE_SKIP.\n\nThe bad behavior was detected by a syzkaller program that toggles port I/O\ninterception during the userspace I/O exit, ultimately resulting in a WARN\non vcpu->arch.pio.count being non-zero due to KVM no completing emulation\nof the I/O instruction.\n\n WARNING: CPU: 23 PID: 1083 at arch/x86/kvm/x86.c:8039 emulator_pio_in_out+0x154/0x170 [kvm]\n Modules linked in: kvm_intel kvm irqbypass\n CPU: 23 UID: 1000 PID: 1083 Comm: repro Not tainted 6.16.0-rc5-c1610d2d66b1-next-vm #74 NONE\n Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015\n RIP: 0010:emulator_pio_in_out+0x154/0x170 [kvm]\n PKRU: 55555554\n Call Trace:\n <TASK>\n kvm_fast_pio+0xd6/0x1d0 [kvm]\n vmx_handle_exit+0x149/0x610 [kvm_intel]\n kvm_arch_vcpu_ioctl_run+0xda8/0x1ac0 [kvm]\n kvm_vcpu_ioctl+0x244/0x8c0 [kvm]\n __x64_sys_ioctl+0x8a/0xd0\n do_syscall_64+0x5d/0xc60\n entry_SYSCALL_64_after_hwframe+0x4b/0x53\n </TASK>"
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}
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],
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"metrics": [
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{
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"cvssV3_1": {
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"version": "3.1",
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"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:H",
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"baseScore": 7.9,
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"baseSeverity": "HIGH"
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},
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"scenarios": [
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{
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"lang": "en",
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"value": "AV:L - Exploitation requires either `KVM_RUN`/`ioctl()` access to `/dev/kvm` on the host or code execution inside a guest running a nested hypervisor; there is no network-reachable path to `x86_emulate_insn()`.\nAC:L - The syzkaller reproducer deterministically toggles the port-I/O bitmap while servicing the `KVM_EXIT_IO` exit, and the guest-side variant only needs a second L1 vCPU to write the bitmap page — the attacker controls both sides of the window, and nested virt is enabled by default on kvm_intel/kvm_amd.\nPR:L - The attacker needs only unprivileged access to `/dev/kvm` (commonly granted via the `kvm` group or a VMM process), or ordinary code execution inside a guest; no root or CAP_SYS_ADMIN in the init namespace is required.\nUI:N - The vCPU thread reaches the buggy re-check on the normal `KVM_RUN` re-entry path after a userspace I/O exit; no victim action is needed.\nS:C - A guest (L1/L2) triggers corrupted state and a WARN/panic in the host kernel's KVM module, crossing the guest-to-host security boundary, and the aborted emulation also crosses the L1/L2 authority boundary by delivering an I/O intercept L1 never legitimately received.\nC:L - The stale `pio.count`/`pio.size` makes the next emulated `in` take the completion path and hand back data captured during the earlier I/O read on L2's behalf, leaking bounded `pio_data` contents across the L1/L2 boundary; the copy is capped at the 1024-byte `read_cache`, so it is not an arbitrary read.\nI:L - KVM injects a nested IOIO VM-exit to L1 for an access it already performed against the host device model (double execution) and subsequently substitutes stale `pio_data` for a real port read, corrupting guest I/O state in a limited, non-arbitrary way.\nA:H - The un-cleared `vcpu->arch.pio.count` trips `WARN_ON_ONCE()` in `emulator_pio_in_out()` in the host kernel — a full host panic on the widely deployed `panic_on_warn=1` configuration — and leaves the vCPU with permanently desynchronized emulation state."
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}
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]
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}
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],
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"affected": [
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "unaffected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"arch/x86/kvm/emulate.c",
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"arch/x86/kvm/kvm_emulate.h",
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"arch/x86/kvm/x86.c"
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],
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"versions": [
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{
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"version": "8a76d7f25f8f24fc5a328c8e15e4a7313cf141b9",
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"lessThan": "a908eca437789589dd4624da428614c1275064dc",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "8a76d7f25f8f24fc5a328c8e15e4a7313cf141b9",
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"lessThan": "00338255bb1f422642fb2798ebe92e93b6e4209b",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "8a76d7f25f8f24fc5a328c8e15e4a7313cf141b9",
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"lessThan": "e0ce3ed1048a47986d15aef1a98ebda25560d257",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "8a76d7f25f8f24fc5a328c8e15e4a7313cf141b9",
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"lessThan": "ba35a5d775799ce5ad60230be97336f2fefd518e",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "8a76d7f25f8f24fc5a328c8e15e4a7313cf141b9",
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"lessThan": "3d3abf3f7e8b1abb082070a343de82d7efc80523",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "8a76d7f25f8f24fc5a328c8e15e4a7313cf141b9",
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"lessThan": "e7177c7e32cb806f348387b7f4faafd4a5b32054",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "8a76d7f25f8f24fc5a328c8e15e4a7313cf141b9",
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"lessThan": "3a062a5c55adc5507600b9ae6d911e247e2f1d6e",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "8a76d7f25f8f24fc5a328c8e15e4a7313cf141b9",
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"lessThan": "7366830642505683bbe905a2ba5d18d6e4b512b8",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "8a76d7f25f8f24fc5a328c8e15e4a7313cf141b9",
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"lessThan": "e750f85391286a4c8100275516973324b621a269",
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"status": "affected",
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"versionType": "git"
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}
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]
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},
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "affected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"arch/x86/kvm/emulate.c",
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"arch/x86/kvm/kvm_emulate.h",
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"arch/x86/kvm/x86.c"
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],
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"versions": [
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{
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"version": "3.0",
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"status": "affected"
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},
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{
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"version": "0",
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"lessThan": "3.0",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "5.4.301",
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"lessThanOrEqual": "5.4.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "5.10.246",
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"lessThanOrEqual": "5.10.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "5.15.195",
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"lessThanOrEqual": "5.15.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.1.157",
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"lessThanOrEqual": "6.1.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.6.111",
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"lessThanOrEqual": "6.6.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.12.52",
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"lessThanOrEqual": "6.12.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.16.12",
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"lessThanOrEqual": "6.16.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.17.2",
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"lessThanOrEqual": "6.17.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.18",
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"lessThanOrEqual": "*",
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"status": "unaffected",
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"versionType": "original_commit_for_fix"
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}
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]
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}
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],
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"cpeApplicability": [
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{
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"nodes": [
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{
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"operator": "OR",
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"negate": false,
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"cpeMatch": [
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "3.0",
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"versionEndExcluding": "5.4.301"
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},
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "3.0",
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"versionEndExcluding": "5.10.246"
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},
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "3.0",
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"versionEndExcluding": "5.15.195"
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},
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "3.0",
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"versionEndExcluding": "6.1.157"
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},
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "3.0",
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"versionEndExcluding": "6.6.111"
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},
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "3.0",
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"versionEndExcluding": "6.12.52"
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},
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "3.0",
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"versionEndExcluding": "6.16.12"
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},
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "3.0",
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"versionEndExcluding": "6.17.2"
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},
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "3.0",
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"versionEndExcluding": "6.18"
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}
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]
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}
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]
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}
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],
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"references": [
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{
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"url": "https://git.kernel.org/stable/c/a908eca437789589dd4624da428614c1275064dc"
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},
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{
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"url": "https://git.kernel.org/stable/c/00338255bb1f422642fb2798ebe92e93b6e4209b"
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},
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{
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"url": "https://git.kernel.org/stable/c/e0ce3ed1048a47986d15aef1a98ebda25560d257"
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},
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{
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"url": "https://git.kernel.org/stable/c/ba35a5d775799ce5ad60230be97336f2fefd518e"
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},
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{
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"url": "https://git.kernel.org/stable/c/3d3abf3f7e8b1abb082070a343de82d7efc80523"
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},
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{
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"url": "https://git.kernel.org/stable/c/e7177c7e32cb806f348387b7f4faafd4a5b32054"
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},
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{
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"url": "https://git.kernel.org/stable/c/3a062a5c55adc5507600b9ae6d911e247e2f1d6e"
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},
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{
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"url": "https://git.kernel.org/stable/c/7366830642505683bbe905a2ba5d18d6e4b512b8"
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},
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{
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"url": "https://git.kernel.org/stable/c/e750f85391286a4c8100275516973324b621a269"
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}
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],
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"title": "KVM: x86: Don't (re)check L1 intercepts when completing userspace I/O",
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"x_generator": {
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"engine": "bippy-1.2.0"
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}
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},
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"adp": [
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{
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"metrics": [
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{
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"other": {
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"type": "ssvc",
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"content": {
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"id": "CVE-2025-40026",
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"role": "CISA Coordinator",
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"options": [
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{
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"Exploitation": "none"
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},
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{
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"Automatable": "no"
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},
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{
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"Technical Impact": "partial"
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}
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],
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"version": "2.0.3",
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"timestamp": "2026-10-15T21:56:14.274469Z"
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}
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}
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}
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],
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"title": "CISA ADP Vulnrichment",
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"providerMetadata": {
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"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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"shortName": "CISA-ADP",
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"dateUpdated": "2026-10-15T22:02:36.361Z"
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}
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}
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]
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}
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} |