CVE-2025-39977
Estado: AplazadaAlta (7.8)—
In the Linux kernel, the following vulnerability has been resolved:
futex: Prevent use-after-free during requeue-PI
syzbot managed to trigger the following race:
In this scenario futex_wait_requeue_pi() is able to leave without using futex_q::lock_ptr for synchronization.
This can be prevented by reading futex_q::task before updating the futex_q::requeue_state. A reference on the task_struct is not needed because requeue_pi_wake_futex() is invoked with a spinlock_t held which implies a RCU read section.
Even if T1 terminates immediately after, the task_struct will remain valid during T2's wake_up_state(). A READ_ONCE on futex_q::task before futex_requeue_pi_complete() is enough because it ensures that the variable is read before the state is updated.
Leer descripción completaMostrar menos
Read futex_q::task before updating the requeue state, use it for the following wakeup.
Detalles técnicos trazas, registros y código del informe original
T1 T2
futex_wait_requeue_pi()
futex_do_wait()
schedule()
futex_requeue()
futex_proxy_trylock_atomic()
futex_requeue_pi_prepare()
requeue_pi_wake_futex()
futex_requeue_pi_complete()
/* preempt */
* timeout/ signal wakes T1 *
futex_requeue_pi_wakeup_sync() // Q_REQUEUE_PI_LOCKED
futex_hash_put()
// back to userland, on stack futex_q is garbage
/* back */
wake_up_state(q->task, TASK_NORMAL);CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Puntuación base: 7.8
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.15%
- Percentil entre todas las CVEs puntuadas: 4
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
🎯 Técnicas ATT&CK
Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.
- Explotación
T1068Exploitation for Privilege Escalationprivilege escalation85 % - Impacto principal
T1499.004Application or System Exploitationimpact75 %
Vulnerabilidad de use-after-free en kernel Linux con acceso local privilegiado (PR:L). El impacto es denial of service por corrupción de memoria en condición de carrera (race condition) durante requeue-PI de futex.
Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.
🛡️ Mitigaciones ATT&CK que cubren estas técnicas
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
Referencias
- https://git.kernel.org/stable/c/348736955ed6ca6e99ca24b93b1d3fbfe352c181
- https://git.kernel.org/stable/c/a170b9c0dde83312b8b58ccc91509c7c15711641
- https://git.kernel.org/stable/c/b549113738e8c751b613118032a724b772aa83f2
- https://git.kernel.org/stable/c/cb5d19a61274b51b49601214a87af573b43d60fa
- https://git.kernel.org/stable/c/d824b2dbdcfe3c390278dd9652ea526168ef6850
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html
- https://cert-portal.siemens.com/productcert/html/ssa-082556.html
JSON original (NVD)
Mostrar
{
"id": "CVE-2025-39977",
"cveTags": [],
"metrics": {
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{
"type": "Secondary",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"cvssData": {
"scope": "UNCHANGED",
"version": "3.1",
"baseScore": 7.8,
"attackVector": "LOCAL",
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"integrityImpact": "HIGH",
"userInteraction": "NONE",
"attackComplexity": "LOW",
"availabilityImpact": "HIGH",
"privilegesRequired": "LOW",
"confidentialityImpact": "HIGH"
},
"impactScore": 5.9,
"exploitabilityScore": 1.8
}
]
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{
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{
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}
],
"defaultStatus": "unknown"
},
{
"vendor": "Siemens",
"product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP",
"versions": [
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{
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{
"vendor": "Siemens",
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],
"published": "2025-10-15T08:15:35.517",
"references": [
{
"url": "https://git.kernel.org/stable/c/348736955ed6ca6e99ca24b93b1d3fbfe352c181",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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{
"url": "https://git.kernel.org/stable/c/a170b9c0dde83312b8b58ccc91509c7c15711641",
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{
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{
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{
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},
{
"url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html",
"source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"
},
{
"url": "https://cert-portal.siemens.com/productcert/html/ssa-082556.html",
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}
],
"vulnStatus": "Deferred",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfutex: Prevent use-after-free during requeue-PI\n\nsyzbot managed to trigger the following race:\n\n T1 T2\n\n futex_wait_requeue_pi()\n futex_do_wait()\n schedule()\n futex_requeue()\n futex_proxy_trylock_atomic()\n futex_requeue_pi_prepare()\n requeue_pi_wake_futex()\n futex_requeue_pi_complete()\n /* preempt */\n\n * timeout/ signal wakes T1 *\n\n futex_requeue_pi_wakeup_sync() // Q_REQUEUE_PI_LOCKED\n futex_hash_put()\n // back to userland, on stack futex_q is garbage\n\n /* back */\n wake_up_state(q->task, TASK_NORMAL);\n\nIn this scenario futex_wait_requeue_pi() is able to leave without using\nfutex_q::lock_ptr for synchronization.\n\nThis can be prevented by reading futex_q::task before updating the\nfutex_q::requeue_state. A reference on the task_struct is not needed\nbecause requeue_pi_wake_futex() is invoked with a spinlock_t held which\nimplies a RCU read section.\n\nEven if T1 terminates immediately after, the task_struct will remain valid\nduring T2's wake_up_state(). A READ_ONCE on futex_q::task before\nfutex_requeue_pi_complete() is enough because it ensures that the variable\nis read before the state is updated.\n\nRead futex_q::task before updating the requeue state, use it for the\nfollowing wakeup."
}
],
"lastModified": "2026-07-30T06:24:03.663",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}