310 lines
18 KiB
JSON
310 lines
18 KiB
JSON
{
|
|
"dataType": "CVE_RECORD",
|
|
"dataVersion": "5.2",
|
|
"cveMetadata": {
|
|
"cveId": "CVE-2026-63806",
|
|
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
|
|
"state": "PUBLISHED",
|
|
"assignerShortName": "Linux",
|
|
"dateReserved": "2026-07-19T07:54:57.013Z",
|
|
"datePublished": "2026-07-19T12:02:10.209Z",
|
|
"dateUpdated": "2026-10-19T20:07:48.133Z"
|
|
},
|
|
"containers": {
|
|
"cna": {
|
|
"providerMetadata": {
|
|
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
|
|
"shortName": "Linux",
|
|
"dateUpdated": "2026-08-17T04:51:12.196Z"
|
|
},
|
|
"descriptions": [
|
|
{
|
|
"lang": "en",
|
|
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: Replace guest-triggerable BUG_ON() in ioeventfd datamatch with get_unaligned()\n\nDrop a BUG_ON() that has been reachable since it was first added, way back\nin 2009, and instead use get_unaligned() to perform potentially-unaligned\naccesses.\n\nFor a given store, KVM x86's emulator tracks the entire value in the\ndestination operand, x86_emulate_ctxt.dst. If the destination is memory,\nand the target splits multiple pages and/or is emulated MMIO, then KVM\nhandles each fragment independently. E.g. on a page split starting at page\noffset 0xffc, KVM writes 4 bytes to the first page, then the remaining\nbytes to the second page, using ctxt->dst as the source for both (with\nappropriate offsets).\n\nIf the destination splits a page *and* hits emulated MMIO on the second\npage, then KVM will complete the write to the first page, then emulate the\nMMIO access to the second page. If there is a datamatch-enabled ioeventfd\nat offset 0 of the second page, then KVM will process the remainder of the\nstore as a potential ioeventfd signal.\n\nPutting it all together, if the guest emits a store that splits a page\nstarting at page offset N, and the second page has a datamatch-enabled\nioeventfd at offset 0, then KVM will check for datamatch using\n&dst.valptr[N] as the source. Due to dst (and thus dst.valptr) being\n32-byte aligned, if N is not aligned to @len, the BUG_ON() fires.\n\nE.g. with a 16-byte store at page offset 0xffc, to an ioeventfd of len 8,\nall initial checks in ioeventfd_in_range() will succeed, and the BUG_ON()\nfires due to @val being 4-byte aligned, but not 8-byte aligned.\n\n ------------[ cut here ]------------\n kernel BUG at arch/x86/kvm/../../../virt/kvm/eventfd.c:783!\n Oops: invalid opcode: 0000 [#1] SMP\n CPU: 0 UID: 1000 PID: 615 Comm: repro Not tainted 7.1.0-rc2-ff238429d1ea #365 PREEMPT\n Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015\n RIP: 0010:ioeventfd_write+0x6c/0x70 [kvm]\n Call Trace:\n <TASK>\n __kvm_io_bus_write+0x85/0xb0 [kvm]\n kvm_io_bus_write+0x53/0x80 [kvm]\n vcpu_mmio_write+0x66/0xf0 [kvm]\n emulator_read_write_onepage+0x12a/0x540 [kvm]\n emulator_read_write+0x109/0x2b0 [kvm]\n x86_emulate_insn+0x4f8/0xfb0 [kvm]\n x86_emulate_instruction+0x181/0x790 [kvm]\n kvm_mmu_page_fault+0x313/0x630 [kvm]\n vmx_handle_exit+0x18a/0x590 [kvm_intel]\n kvm_arch_vcpu_ioctl_run+0xc81/0x1c90 [kvm]\n kvm_vcpu_ioctl+0x2d5/0x970 [kvm]\n __x64_sys_ioctl+0x8a/0xd0\n do_syscall_64+0xb7/0x890\n entry_SYSCALL_64_after_hwframe+0x4b/0x53\n RIP: 0033:0x7f19c931a9bf\n </TASK>\n Modules linked in: kvm_intel kvm irqbypass\n ---[ end trace 0000000000000000 ]---\n\nIn a perfect world, the fix would be to simply delete the BUG_ON(), as KVM\nx86 doesn't perform alignment checks on \"normal\" memory accesses at CPL0.\nSadly, C99 ruins all the fun; while the x86 architecture plays nice,\ndereferencing an unaligned pointer directly is undefined behavior in C,\ne.g. triggers splats when running with CONFIG_UBSAN_ALIGNMENT=y."
|
|
}
|
|
],
|
|
"metrics": [
|
|
{
|
|
"cvssV3_1": {
|
|
"version": "3.1",
|
|
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H",
|
|
"baseScore": 7.1,
|
|
"baseSeverity": "HIGH"
|
|
},
|
|
"scenarios": [
|
|
{
|
|
"lang": "en",
|
|
"value": "AV:L - A malicious KVM guest triggers this via guest-executed MMIO stores handled by the x86 instruction emulator (KVM_RUN → vmx_handle_exit → kvm_mmu_page_fault → x86_emulate_instruction → emulator_read_write → vcpu_mmio_write → ioeventfd_write), not via remote network input to the host.\nAC:L - The guest fully controls the spanning store address, size, and timing; with standard QEMU/virtio datamatch ioeventfd MMIO layouts, a page-boundary write reliably reaches ioeventfd_in_range() with a misaligned val pointer and fires the BUG_ON().\nPR:N - Exploitation requires only unprivileged code execution inside an already-running guest VM (reproducer ran as UID 1000); no host capabilities, KVM ioctls, or guest root are needed beyond what any cloud VM tenant or compromised guest process already has.\nUI:N - No victim interaction is required once the attacker can run code in a KVM guest with a datamatch ioeventfd configured, which is the default virtio/QEMU setup.\nS:C - The vulnerable component is the host kernel KVM subsystem, but exploitation is initiated from a guest VM and causes a host kernel BUG/oops, crossing the hypervisor security boundary.\nC:N - The failure mode is an explicit BUG_ON() alignment check before any datamatch comparison; there is no out-of-bounds read, use-after-free, or other memory corruption that could disclose host data.\nI:N - The bug triggers a deliberate kernel BUG and does not corrupt or modify host memory; it is a crash-only denial-of-service with no integrity impact.\nA:H - A guest-triggered BUG_ON() in ioeventfd_write() causes a host kernel oops/panic, denying availability of the entire physical host and all co-resident VMs on multi-tenant KVM hypervisors."
|
|
}
|
|
]
|
|
}
|
|
],
|
|
"affected": [
|
|
{
|
|
"product": "Linux",
|
|
"vendor": "Linux",
|
|
"defaultStatus": "unaffected",
|
|
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
|
|
"programFiles": [
|
|
"virt/kvm/eventfd.c"
|
|
],
|
|
"versions": [
|
|
{
|
|
"version": "d34e6b175e61821026893ec5298cc8e7558df43a",
|
|
"lessThan": "2426c15c1395b7d5ccf1e5025ca898af7f3decb6",
|
|
"status": "affected",
|
|
"versionType": "git"
|
|
},
|
|
{
|
|
"version": "d34e6b175e61821026893ec5298cc8e7558df43a",
|
|
"lessThan": "4186c850789906b875a1d263377a4d37c078e317",
|
|
"status": "affected",
|
|
"versionType": "git"
|
|
},
|
|
{
|
|
"version": "d34e6b175e61821026893ec5298cc8e7558df43a",
|
|
"lessThan": "36ff44fb3d89960391e013fb9d91e23dbc48be47",
|
|
"status": "affected",
|
|
"versionType": "git"
|
|
},
|
|
{
|
|
"version": "d34e6b175e61821026893ec5298cc8e7558df43a",
|
|
"lessThan": "92fc631b69deb1c7d56aec2663003600799dcd75",
|
|
"status": "affected",
|
|
"versionType": "git"
|
|
},
|
|
{
|
|
"version": "d34e6b175e61821026893ec5298cc8e7558df43a",
|
|
"lessThan": "bf89e3738480d33cd515b4a18900e8443d40cd2e",
|
|
"status": "affected",
|
|
"versionType": "git"
|
|
},
|
|
{
|
|
"version": "d34e6b175e61821026893ec5298cc8e7558df43a",
|
|
"lessThan": "5da9b1a87ec7cc3489c27016313524769f12d9e0",
|
|
"status": "affected",
|
|
"versionType": "git"
|
|
},
|
|
{
|
|
"version": "d34e6b175e61821026893ec5298cc8e7558df43a",
|
|
"lessThan": "5c87b47374682f69686068ad0a7779365a527b1c",
|
|
"status": "affected",
|
|
"versionType": "git"
|
|
},
|
|
{
|
|
"version": "d34e6b175e61821026893ec5298cc8e7558df43a",
|
|
"lessThan": "f1edbed787ba67988ed34e0132ca128b052b6ce8",
|
|
"status": "affected",
|
|
"versionType": "git"
|
|
}
|
|
]
|
|
},
|
|
{
|
|
"product": "Linux",
|
|
"vendor": "Linux",
|
|
"defaultStatus": "affected",
|
|
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
|
|
"programFiles": [
|
|
"virt/kvm/eventfd.c"
|
|
],
|
|
"versions": [
|
|
{
|
|
"version": "2.6.32",
|
|
"status": "affected"
|
|
},
|
|
{
|
|
"version": "0",
|
|
"lessThan": "2.6.32",
|
|
"status": "unaffected",
|
|
"versionType": "semver"
|
|
},
|
|
{
|
|
"version": "5.10.261",
|
|
"lessThanOrEqual": "5.10.*",
|
|
"status": "unaffected",
|
|
"versionType": "semver"
|
|
},
|
|
{
|
|
"version": "5.15.212",
|
|
"lessThanOrEqual": "5.15.*",
|
|
"status": "unaffected",
|
|
"versionType": "semver"
|
|
},
|
|
{
|
|
"version": "6.1.178",
|
|
"lessThanOrEqual": "6.1.*",
|
|
"status": "unaffected",
|
|
"versionType": "semver"
|
|
},
|
|
{
|
|
"version": "6.6.145",
|
|
"lessThanOrEqual": "6.6.*",
|
|
"status": "unaffected",
|
|
"versionType": "semver"
|
|
},
|
|
{
|
|
"version": "6.12.95",
|
|
"lessThanOrEqual": "6.12.*",
|
|
"status": "unaffected",
|
|
"versionType": "semver"
|
|
},
|
|
{
|
|
"version": "6.18.38",
|
|
"lessThanOrEqual": "6.18.*",
|
|
"status": "unaffected",
|
|
"versionType": "semver"
|
|
},
|
|
{
|
|
"version": "7.1.3",
|
|
"lessThanOrEqual": "7.1.*",
|
|
"status": "unaffected",
|
|
"versionType": "semver"
|
|
},
|
|
{
|
|
"version": "7.2",
|
|
"lessThanOrEqual": "*",
|
|
"status": "unaffected",
|
|
"versionType": "original_commit_for_fix"
|
|
}
|
|
]
|
|
}
|
|
],
|
|
"cpeApplicability": [
|
|
{
|
|
"nodes": [
|
|
{
|
|
"operator": "OR",
|
|
"negate": false,
|
|
"cpeMatch": [
|
|
{
|
|
"vulnerable": true,
|
|
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
|
|
"versionStartIncluding": "2.6.32",
|
|
"versionEndExcluding": "5.10.261"
|
|
},
|
|
{
|
|
"vulnerable": true,
|
|
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
|
|
"versionStartIncluding": "2.6.32",
|
|
"versionEndExcluding": "5.15.212"
|
|
},
|
|
{
|
|
"vulnerable": true,
|
|
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
|
|
"versionStartIncluding": "2.6.32",
|
|
"versionEndExcluding": "6.1.178"
|
|
},
|
|
{
|
|
"vulnerable": true,
|
|
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
|
|
"versionStartIncluding": "2.6.32",
|
|
"versionEndExcluding": "6.6.145"
|
|
},
|
|
{
|
|
"vulnerable": true,
|
|
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
|
|
"versionStartIncluding": "2.6.32",
|
|
"versionEndExcluding": "6.12.95"
|
|
},
|
|
{
|
|
"vulnerable": true,
|
|
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
|
|
"versionStartIncluding": "2.6.32",
|
|
"versionEndExcluding": "6.18.38"
|
|
},
|
|
{
|
|
"vulnerable": true,
|
|
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
|
|
"versionStartIncluding": "2.6.32",
|
|
"versionEndExcluding": "7.1.3"
|
|
},
|
|
{
|
|
"vulnerable": true,
|
|
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
|
|
"versionStartIncluding": "2.6.32",
|
|
"versionEndExcluding": "7.2"
|
|
}
|
|
]
|
|
}
|
|
]
|
|
}
|
|
],
|
|
"references": [
|
|
{
|
|
"url": "https://git.kernel.org/stable/c/2426c15c1395b7d5ccf1e5025ca898af7f3decb6"
|
|
},
|
|
{
|
|
"url": "https://git.kernel.org/stable/c/4186c850789906b875a1d263377a4d37c078e317"
|
|
},
|
|
{
|
|
"url": "https://git.kernel.org/stable/c/36ff44fb3d89960391e013fb9d91e23dbc48be47"
|
|
},
|
|
{
|
|
"url": "https://git.kernel.org/stable/c/92fc631b69deb1c7d56aec2663003600799dcd75"
|
|
},
|
|
{
|
|
"url": "https://git.kernel.org/stable/c/bf89e3738480d33cd515b4a18900e8443d40cd2e"
|
|
},
|
|
{
|
|
"url": "https://git.kernel.org/stable/c/5da9b1a87ec7cc3489c27016313524769f12d9e0"
|
|
},
|
|
{
|
|
"url": "https://git.kernel.org/stable/c/5c87b47374682f69686068ad0a7779365a527b1c"
|
|
},
|
|
{
|
|
"url": "https://git.kernel.org/stable/c/f1edbed787ba67988ed34e0132ca128b052b6ce8"
|
|
}
|
|
],
|
|
"title": "KVM: Replace guest-triggerable BUG_ON() in ioeventfd datamatch with get_unaligned()",
|
|
"x_generator": {
|
|
"engine": "bippy-1.2.0"
|
|
}
|
|
},
|
|
"adp": [
|
|
{
|
|
"metrics": [
|
|
{
|
|
"other": {
|
|
"type": "ssvc",
|
|
"content": {
|
|
"id": "CVE-2026-63806",
|
|
"role": "CISA Coordinator",
|
|
"options": [
|
|
{
|
|
"Exploitation": "none"
|
|
},
|
|
{
|
|
"Automatable": "no"
|
|
},
|
|
{
|
|
"Technical Impact": "partial"
|
|
}
|
|
],
|
|
"version": "2.0.3",
|
|
"timestamp": "2026-10-16T15:30:51.657240Z"
|
|
}
|
|
}
|
|
}
|
|
],
|
|
"problemTypes": [
|
|
{
|
|
"descriptions": [
|
|
{
|
|
"lang": "en",
|
|
"type": "CWE",
|
|
"cweId": "CWE-400",
|
|
"description": "CWE-400 Uncontrolled Resource Consumption"
|
|
}
|
|
]
|
|
}
|
|
],
|
|
"title": "CISA ADP Vulnrichment",
|
|
"providerMetadata": {
|
|
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
|
|
"shortName": "CISA-ADP",
|
|
"dateUpdated": "2026-10-19T20:07:48.133Z"
|
|
}
|
|
}
|
|
]
|
|
}
|
|
} |