{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-90003","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-09-11T19:38:34.780Z","datePublished":"2026-09-16T10:33:13.420Z","dateUpdated":"2026-09-16T14:41:20.519Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-09-16T14:41:20.519Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nfutex: Prevent rcuwait use-after-free during requeue PI\n\nOn PREEMPT_RT, FUTEX_CMP_REQUEUE_PI can trigger a KASAN report\n(slab-out-of-bounds) in futex_requeue_pi_complete() invocation of\nrcuwait_wake_up().\n\nThe futex_q used by futex_wait_requeue_pi() is allocated on the waiter's\nstack. An early wakeup can race with a PI requeue as follows:\n\n        waiter                          requeue task\n        ------                          ------------\nfutex_wait_requeue_pi()\n  futex_do_wait()\n    schedule()\n                                       futex_requeue\n                                         futex_proxy_trylock_atomic()\n                                           futex_requeue_pi_prepare()\n                                            Q_REQUEUE_PI_NONE -> Q_REQUEUE_PI_IN_PROGRESS\n* timeout/ signal wakes waiter *\n  futex_requeue_pi_wakeup_sync()\n   Q_REQUEUE_PI_IN_PROGRESS -> Q_REQUEUE_PI_WAIT\n                                           requeue_pi_wake_futex\n                                             futex_requeue_pi_complete()\n                                               cmpxchg Q_REQUEUE_PI_WAIT -> Q_REQUEUE_PI_LOCKED\n    rcuwait_wait_event()\n      if (atomic_read(&q->requeue_state) != Q_REQUEUE_PI_WAIT)\n       break /* no schedule() */\n\n /* q.pi_state->owner == current */\n futex_private_hash_put()\n /* return from syscall */\n                                              rcuwait_wake_up(&q->requeue_wait)\n                                                /* q is gone */\n\nfutex_requeue_pi_complete() publishes Q_REQUEUE_PI_LOCKED before\ncalling rcuwait_wake_up(). The waiter observes this state in\nrcuwait_wait_event() before invoking schedule() in rcuwait_wait_event().\nHere, the waiter is free leave the syscall before requeue task can\ncomplete the wake.\n\nTo address this race skip rcuwait_wake_up() in the Q_REQUEUE_PI_LOCKED\ncase.\nThis state is only published by requeue_pi_wake_futex(), which saves\nq->task before futex_requeue_pi_complete() and wakes the waiter via\nwake_up_state().\n\nThis wake is intended to wake the waiter from its futex_do_wait() sleep.\nIf the waiter is still sleeping there, it can not get into the\nQ_REQUEUE_PI_WAIT state (and require this removed wake).\nShould the waiter be woken up from futex_do_wait() by other means (as in\nthis example) and sleep in futex_requeue_pi_wakeup_sync() then the\nwake_up_state() from requeue_pi_wake_futex() will wake it, too.\nShould the waiter task terminate before wake_up_state() had a chance to\nwake the task then the task pointer does not become invalid because the\nfutex_hash_bucket::lock is held and the task pointer is RCU protected.\n\n[bigeasy: Updated comment and commit message]"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The bug is reached only through the local futex(2) syscalls FUTEX_WAIT_REQUEUE_PI and FUTEX_CMP_REQUEUE_PI into kernel/futex/requeue.c; there is no network, Bluetooth, or physical-device path.\nAC:L - The attacker controls both sides of the race: a waiter thread using FUTEX_WAIT_REQUEUE_PI with an attacker-chosen timeout or signal, and a concurrent FUTEX_CMP_REQUEUE_PI from another thread, and can retry with CPU pinning until the waiter returns before rcuwait_wake_up() on PREEMPT_RT.\nPR:L - Any unprivileged local user can invoke futex() with FUTEX_WAIT_REQUEUE_PI and FUTEX_CMP_REQUEUE_PI; do_futex() and futex_requeue() perform no capability or credential checks, CONFIG_FUTEX_PI is default-y, and the path is reachable from containers without elevated privileges.\nUI:N - The attacker's own threads perform the wait, timeout or signal, and PI requeue; no victim action such as mounting a filesystem or opening a file is required.\nS:U - The use-after-free corrupts kernel memory (the waiter's stack-allocated futex_q and a type-confused task_struct) within the same kernel security authority; this is a standard local privilege-escalation issue, not a VM, IOMMU, or hypervisor escape.\nC:H - This is a use-after-free of the waiter's stack-allocated futex_q.requeue_wait; rcuwait_wake_up() reads a stale, attacker-refilled task_struct pointer and dereferences it in try_to_wake_up(), enabling arbitrary kernel-memory disclosure.\nI:H - The stale futex_q lives on the attacker's own kernel stack, which a following syscall can refill with controlled bytes, so rcuwait_wake_up() passes an attacker-chosen pointer into try_to_wake_up(), which writes task state and makes indirect scheduler calls, enabling privilege escalation.\nA:H - In the unexploited case, rcuwait_wake_up() dereferences a wild pointer from reused stack memory and causes a kernel oops or panic; any use-after-free of this kind is a High availability impact."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/futex/requeue.c"],"versions":[{"version":"07d91ef510fb16a2e0ca7453222105835b7ba3b8","lessThan":"220ee9e04ca3b7f014c000264aa6c884f036c86e","status":"affected","versionType":"git"},{"version":"07d91ef510fb16a2e0ca7453222105835b7ba3b8","lessThan":"81aadbd09bf1dcd3238212f336ba699503557ae8","status":"affected","versionType":"git"},{"version":"07d91ef510fb16a2e0ca7453222105835b7ba3b8","lessThan":"244f301759fd34b1dd0b4192ce44f8ef224e027d","status":"affected","versionType":"git"},{"version":"07d91ef510fb16a2e0ca7453222105835b7ba3b8","lessThan":"7d1559126d86be6e4f6a85663dfbfe85caa47e37","status":"affected","versionType":"git"},{"version":"07d91ef510fb16a2e0ca7453222105835b7ba3b8","lessThan":"e4a4ccfa470f910b747b3ee8d18670ed8ac8a236","status":"affected","versionType":"git"},{"version":"07d91ef510fb16a2e0ca7453222105835b7ba3b8","lessThan":"a3b8d46fe401cba3a5c46dea610e6eb3dc15370e","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/futex/requeue.c"],"versions":[{"version":"5.15","status":"affected"},{"version":"0","lessThan":"5.15","status":"unaffected","versionType":"semver"},{"version":"6.1.188","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.157","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.110","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.51","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.5","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3-rc2","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":"5.15","versionEndExcluding":"6.1.188"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.6.157"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.12.110"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.18.51"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"7.2.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"7.3-rc2"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/220ee9e04ca3b7f014c000264aa6c884f036c86e"},{"url":"https://git.kernel.org/stable/c/81aadbd09bf1dcd3238212f336ba699503557ae8"},{"url":"https://git.kernel.org/stable/c/244f301759fd34b1dd0b4192ce44f8ef224e027d"},{"url":"https://git.kernel.org/stable/c/7d1559126d86be6e4f6a85663dfbfe85caa47e37"},{"url":"https://git.kernel.org/stable/c/e4a4ccfa470f910b747b3ee8d18670ed8ac8a236"},{"url":"https://git.kernel.org/stable/c/a3b8d46fe401cba3a5c46dea610e6eb3dc15370e"}],"title":"futex: Prevent rcuwait use-after-free during requeue PI","x_generator":{"engine":"bippy-1.2.0"}}}}