159 lines
9.5 KiB
JSON
159 lines
9.5 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-2026-90317",
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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": "2026-09-11T19:38:34.801Z",
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"datePublished": "2026-09-17T16:08:35.537Z",
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"dateUpdated": "2026-10-19T09:01:33.647Z"
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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": "2026-10-19T09:01:33.647Z"
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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\nbpf: Invalidate RCU pointers after final spin unlock\n\nIn a sleepable BPF program, a spin lock can provide the only RCU protection\nfor a kptr. The final bpf_spin_unlock() ends that protection, but the\nverifier leaves the pointer valid. Another CPU can then free the object\nbefore the pointer is used. A capability-limited runtime PoC triggered a\ntask_struct use-after-free in __bpf_get_task_stack().\n\nRecord whether the program is in an RCU-protected context before releasing\nthe lock. Invalidate RCU-protected pointers only when the unlock leaves the\nfinal such context. This preserves valid pointers in non-sleepable programs\nand inside an explicit RCU read-side section."
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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:U/C:H/I:H/A:H",
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"baseScore": 7.8,
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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 - The attacker-controlled input is a sleepable BPF program loaded via bpf(BPF_PROG_LOAD) whose bytecode reaches process_spin_lock() in kernel/bpf/verifier.c, takes bpf_spin_lock, LDXes a map kptr, then bpf_spin_unlock. That program image arrives through the local bpf() syscall, not a network protocol message.\nAC:L - The attacker drives both sides: a sleepable fentry.s or BPF_PROG_TYPE_SYSCALL program loads a task kptr under bpf_spin_lock, unlocks, then uses it, while another thread bpf_kptr_xchg's the same slot to NULL so bpf_task_release_dtor/put_task_struct_rcu_user can call_rcu it. After unlock, preempt/IRQs are re-enabled so the grace period can finish; a PoC hit the UAF.\nPR:L - A sleepable BPF_PROG_TYPE_SYSCALL program is sufficient: bpf_prog_load() requires only bpf_token_capable(CAP_BPF) because is_perfmon_prog_type() is false for SYSCALL, and map_check_btf() needs CAP_BPF for BPF_SPIN_LOCK|BPF_KPTR fields. CAP_BPF is delegable via BPF tokens into a user namespace; the report used a capability-limited PoC, not init-namespace root.\nUI:N - The attacker loads the sleepable program, creates the lock+kptr ARRAY map, stores a task with bpf_task_from_pid/bpf_kptr_xchg, and runs it via bpf(BPF_PROG_TEST_RUN) (bpf_prog_test_run_syscall) or by calling getpgid after attaching fentry.s; no victim mount or file open is required.\nS:U - The use-after-free is of a host kernel task_struct consumed by bpf_task_acquire and __bpf_get_task_stack in the same kernel that accepted the program. That is local privilege escalation inside one kernel authority, not a VM, IOMMU, or guest-to-host crossing.\nC:H - After the final bpf_spin_unlock, process_spin_lock() leaves the map-loaded task kptr as MEM_RCU, so the program can LDX task_struct fields or call bpf_task_acquire (refcount_inc_not_zero on rcu_users) and __bpf_get_task_stack (try_get_task_stack/task_pt_regs) on a call_rcu-freed object. Spraying that slot yields an arbitrary kernel read.\nI:H - The same stale MEM_RCU task_struct pointer can be passed to bpf_task_acquire after bpf_task_release_dtor has dropped rcu_users and delayed_put_task_struct has freed it; a sprayed replacement becomes an owned kptr the attacker can feed to other kfuncs or store back with bpf_kptr_xchg, giving a write and control-flow primitive.\nA:H - Using the dangling task pointer in __bpf_get_task_stack (try_get_task_stack/task_pt_regs) or bpf_task_acquire after put_task_struct_rcu_user's call_rcu has run oopses or panics the kernel even without a full exploit."
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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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"kernel/bpf/verifier.c"
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],
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"versions": [
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{
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"version": "5861d1e8dbc4e1a03ebffb96ac041026cdd34c07",
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"lessThan": "f81972b235f3ebfa40bdce8bcfee3f242fb24065",
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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": "5861d1e8dbc4e1a03ebffb96ac041026cdd34c07",
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"lessThan": "7ae71629357d0a6d0bdadb929c7b296d5b7e61c2",
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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": "5861d1e8dbc4e1a03ebffb96ac041026cdd34c07",
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"lessThan": "180c7000712db77063b3a26f4c97e7dd9038f449",
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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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"kernel/bpf/verifier.c"
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],
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"versions": [
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{
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"version": "6.6",
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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": "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": "6.18.57",
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"lessThanOrEqual": "6.18.*",
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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": "7.2.6",
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"lessThanOrEqual": "7.2.*",
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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": "7.3",
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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": "6.6",
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"versionEndExcluding": "6.18.57"
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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": "6.6",
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"versionEndExcluding": "7.2.6"
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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": "6.6",
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"versionEndExcluding": "7.3"
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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/f81972b235f3ebfa40bdce8bcfee3f242fb24065"
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},
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{
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"url": "https://git.kernel.org/stable/c/7ae71629357d0a6d0bdadb929c7b296d5b7e61c2"
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},
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{
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"url": "https://git.kernel.org/stable/c/180c7000712db77063b3a26f4c97e7dd9038f449"
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}
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],
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"title": "bpf: Invalidate RCU pointers after final spin unlock",
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"x_generator": {
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}
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}
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}
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} |