{"resultsPerPage":1,"startIndex":0,"totalResults":1,"format":"NVD_CVE","version":"2.0","timestamp":"2026-04-20T01:55:36.868","vulnerabilities":[{"cve":{"id":"CVE-2025-38349","sourceIdentifier":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","published":"2025-07-18T08:15:27.543","lastModified":"2025-11-18T12:52:07.410","vulnStatus":"Analyzed","cveTags":[],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\neventpoll: don't decrement ep refcount while still holding the ep mutex\n\nJann Horn points out that epoll is decrementing the ep refcount and then\ndoing a\n\n    mutex_unlock(&ep->mtx);\n\nafterwards. That's very wrong, because it can lead to a use-after-free.\n\nThat pattern is actually fine for the very last reference, because the\ncode in question will delay the actual call to \"ep_free(ep)\" until after\nit has unlocked the mutex.\n\nBut it's wrong for the much subtler \"next to last\" case when somebody\n*else* may also be dropping their reference and free the ep while we're\nstill using the mutex.\n\nNote that this is true even if that other user is also using the same ep\nmutex: mutexes, unlike spinlocks, can not be used for object ownership,\neven if they guarantee mutual exclusion.\n\nA mutex \"unlock\" operation is not atomic, and as one user is still\naccessing the mutex as part of unlocking it, another user can come in\nand get the now released mutex and free the data structure while the\nfirst user is still cleaning up.\n\nSee our mutex documentation in Documentation/locking/mutex-design.rst,\nin particular the section [1] about semantics:\n\n\t\"mutex_unlock() may access the mutex structure even after it has\n\t internally released the lock already - so it's not safe for\n\t another context to acquire the mutex and assume that the\n\t mutex_unlock() context is not using the structure anymore\"\n\nSo if we drop our ep ref before the mutex unlock, but we weren't the\nlast one, we may then unlock the mutex, another user comes in, drops\n_their_ reference and releases the 'ep' as it now has no users - all\nwhile the mutex_unlock() is still accessing it.\n\nFix this by simply moving the ep refcount dropping to outside the mutex:\nthe refcount itself is atomic, and doesn't need mutex protection (that's\nthe whole _point_ of refcounts: unlike mutexes, they are inherently\nabout object lifetimes)."},{"lang":"es","value":"En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: eventpoll: no decrementar el recuento de referencias de ep mientras se mantiene el mutex de ep. Jann Horn señala que epoll decrementa el recuento de referencias de ep y luego ejecuta un mutex_unlock(&ep->mtx);. Esto es totalmente erróneo, ya que puede provocar un use-after-free. Este patrón funciona correctamente para la última referencia, ya que el código en cuestión retrasará la llamada a \"ep_free(ep)\" hasta después de desbloquear el mutex. Sin embargo, es incorrecto para el caso mucho más sutil del penúltimo, cuando alguien *más* también podría eliminar su referencia y liberar el ep mientras aún usamos el mutex. Cabe destacar que esto es cierto incluso si ese otro usuario también usa el mismo mutex de ep: los mutex, a diferencia de los spinlocks, no se pueden usar para la propiedad de objetos, incluso si garantizan la exclusión mutua. Una operación de desbloqueo de mutex no es atómica, y como un usuario sigue accediendo al mutex durante el proceso de desbloqueo, otro usuario puede acceder y obtener el mutex liberado, liberando así la estructura de datos mientras el primer usuario realiza la limpieza. Consulte nuestra documentación sobre mutex en Documentation/locking/mutex-design.rst, en particular la sección [1] sobre semántica: «mutex_unlock() puede acceder a la estructura del mutex incluso después de haber liberado el bloqueo internamente; por lo tanto, no es seguro que otro contexto adquiera el mutex y asuma que el contexto mutex_unlock() ya no utiliza la estructura». Por lo tanto, si eliminamos nuestra referencia ep antes del desbloqueo del mutex, pero no fuimos los últimos, podríamos desbloquear el mutex; otro usuario entra, elimina su referencia y libera el 'ep', ya que ya no tiene usuarios, todo mientras mutex_unlock() sigue accediendo a él. Arregle esto simplemente moviendo el refcount ep que cae fuera del mutex: el refcount en sí es atómico y no necesita protección de mutex (ese es el _objetivo_ de los refcounts: a diferencia de los mutex, son inherentemente acerca de la duración de los objetos)."}],"metrics":{"cvssMetricV31":[{"source":"nvd@nist.gov","type":"Primary","cvssData":{"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","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":5.9}]},"weaknesses":[{"source":"nvd@nist.gov","type":"Primary","description":[{"lang":"en","value":"CWE-416"}]}],"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.4","versionEndExcluding":"6.6.99","matchCriteriaId":"6197B14F-19E2-414C-B393-7B162D07FCCF"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.7","versionEndExcluding":"6.12.39","matchCriteriaId":"18D57670-11F8-4B5A-AD56-EA32DD0F44E1"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.13","versionEndExcluding":"6.15.7","matchCriteriaId":"F9C46937-5FA9-4335-AD7B-E7FC29453CE1"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.16:rc1:*:*:*:*:*:*","matchCriteriaId":"6D4894DB-CCFE-4602-B1BF-3960B2E19A01"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.16:rc2:*:*:*:*:*:*","matchCriteriaId":"09709862-E348-4378-8632-5A7813EDDC86"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.16:rc3:*:*:*:*:*:*","matchCriteriaId":"415BF58A-8197-43F5-B3D7-D1D63057A26E"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.16:rc4:*:*:*:*:*:*","matchCriteriaId":"A0517869-312D-4429-80C2-561086E1421C"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.16:rc5:*:*:*:*:*:*","matchCriteriaId":"85421F4E-C863-4ABF-B4B4-E887CC2F7F92"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/521e9ff0b67c66a17d6f9593dfccafaa984aae4c","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/605c18698ecfa99165f36b7f59d3ed503e169814","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/6dee745bd0aec9d399df674256e7b1ecdb615444","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/8c2e52ebbe885c7eeaabd3b7ddcdc1246fc400d2","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"]},{"url":"https://project-zero.issues.chromium.org/issues/430541637","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Issue Tracking","Patch"]}]}}]}