FKIE_CVE-2026-90003
Vulnerability from fkie_nvd - Published: 2026-09-16 11:17 - Updated: 2026-09-16 15:18
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved:
futex: Prevent rcuwait use-after-free during requeue PI
On PREEMPT_RT, FUTEX_CMP_REQUEUE_PI can trigger a KASAN report
(slab-out-of-bounds) in futex_requeue_pi_complete() invocation of
rcuwait_wake_up().
The futex_q used by futex_wait_requeue_pi() is allocated on the waiter's
stack. An early wakeup can race with a PI requeue as follows:
waiter requeue task
------ ------------
futex_wait_requeue_pi()
futex_do_wait()
schedule()
futex_requeue
futex_proxy_trylock_atomic()
futex_requeue_pi_prepare()
Q_REQUEUE_PI_NONE -> Q_REQUEUE_PI_IN_PROGRESS
* timeout/ signal wakes waiter *
futex_requeue_pi_wakeup_sync()
Q_REQUEUE_PI_IN_PROGRESS -> Q_REQUEUE_PI_WAIT
requeue_pi_wake_futex
futex_requeue_pi_complete()
cmpxchg Q_REQUEUE_PI_WAIT -> Q_REQUEUE_PI_LOCKED
rcuwait_wait_event()
if (atomic_read(&q->requeue_state) != Q_REQUEUE_PI_WAIT)
break /* no schedule() */
/* q.pi_state->owner == current */
futex_private_hash_put()
/* return from syscall */
rcuwait_wake_up(&q->requeue_wait)
/* q is gone */
futex_requeue_pi_complete() publishes Q_REQUEUE_PI_LOCKED before
calling rcuwait_wake_up(). The waiter observes this state in
rcuwait_wait_event() before invoking schedule() in rcuwait_wait_event().
Here, the waiter is free leave the syscall before requeue task can
complete the wake.
To address this race skip rcuwait_wake_up() in the Q_REQUEUE_PI_LOCKED
case.
This state is only published by requeue_pi_wake_futex(), which saves
q->task before futex_requeue_pi_complete() and wakes the waiter via
wake_up_state().
This wake is intended to wake the waiter from its futex_do_wait() sleep.
If the waiter is still sleeping there, it can not get into the
Q_REQUEUE_PI_WAIT state (and require this removed wake).
Should the waiter be woken up from futex_do_wait() by other means (as in
this example) and sleep in futex_requeue_pi_wakeup_sync() then the
wake_up_state() from requeue_pi_wake_futex() will wake it, too.
Should the waiter task terminate before wake_up_state() had a chance to
wake the task then the task pointer does not become invalid because the
futex_hash_bucket::lock is held and the task pointer is RCU protected.
[bigeasy: Updated comment and commit message]
References
Impacted products
| Vendor | Product | Version |
|---|
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"kernel/futex/requeue.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "220ee9e04ca3b7f014c000264aa6c884f036c86e",
"status": "affected",
"version": "07d91ef510fb16a2e0ca7453222105835b7ba3b8",
"versionType": "git"
},
{
"lessThan": "81aadbd09bf1dcd3238212f336ba699503557ae8",
"status": "affected",
"version": "07d91ef510fb16a2e0ca7453222105835b7ba3b8",
"versionType": "git"
},
{
"lessThan": "244f301759fd34b1dd0b4192ce44f8ef224e027d",
"status": "affected",
"version": "07d91ef510fb16a2e0ca7453222105835b7ba3b8",
"versionType": "git"
},
{
"lessThan": "7d1559126d86be6e4f6a85663dfbfe85caa47e37",
"status": "affected",
"version": "07d91ef510fb16a2e0ca7453222105835b7ba3b8",
"versionType": "git"
},
{
"lessThan": "e4a4ccfa470f910b747b3ee8d18670ed8ac8a236",
"status": "affected",
"version": "07d91ef510fb16a2e0ca7453222105835b7ba3b8",
"versionType": "git"
},
{
"lessThan": "a3b8d46fe401cba3a5c46dea610e6eb3dc15370e",
"status": "affected",
"version": "07d91ef510fb16a2e0ca7453222105835b7ba3b8",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"kernel/futex/requeue.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "5.15"
},
{
"lessThan": "5.15",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.188",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.157",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.110",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.51",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.2.*",
"status": "unaffected",
"version": "7.2.5",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.3-rc2",
"versionType": "original_commit_for_fix"
}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"cveTags": [],
"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\u0027s\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 -\u003e Q_REQUEUE_PI_IN_PROGRESS\n* timeout/ signal wakes waiter *\n futex_requeue_pi_wakeup_sync()\n Q_REQUEUE_PI_IN_PROGRESS -\u003e Q_REQUEUE_PI_WAIT\n requeue_pi_wake_futex\n futex_requeue_pi_complete()\n cmpxchg Q_REQUEUE_PI_WAIT -\u003e Q_REQUEUE_PI_LOCKED\n rcuwait_wait_event()\n if (atomic_read(\u0026q-\u003erequeue_state) != Q_REQUEUE_PI_WAIT)\n break /* no schedule() */\n\n /* q.pi_state-\u003eowner == current */\n futex_private_hash_put()\n /* return from syscall */\n rcuwait_wake_up(\u0026q-\u003erequeue_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-\u003etask 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]"
}
],
"id": "CVE-2026-90003",
"lastModified": "2026-09-16T15:18:24.143",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 7.8,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 1.8,
"impactScore": 5.9,
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
]
},
"published": "2026-09-16T11:17:12.810",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/220ee9e04ca3b7f014c000264aa6c884f036c86e"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/244f301759fd34b1dd0b4192ce44f8ef224e027d"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/7d1559126d86be6e4f6a85663dfbfe85caa47e37"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/81aadbd09bf1dcd3238212f336ba699503557ae8"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/a3b8d46fe401cba3a5c46dea610e6eb3dc15370e"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/e4a4ccfa470f910b747b3ee8d18670ed8ac8a236"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Received"
}
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Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
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vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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