CVE-2026-80808
Estado: RecibidaSin puntuar—
In the Linux kernel, the following vulnerability has been resolved:
ext4: stop retrying saturated xattr cache entries
ext4_xattr_block_set() retries when a cache entry selected for reuse has a saturated reference count after taking the buffer lock. The retry returns to the mbcache lookup without making that entry ineligible, so it can select the same unusable entry indefinitely. A task spinning there can hold the parent directory's i_rwsem and leave concurrent rmdir callers blocked.
Normally a reusable entry has a reference count below EXT4_XATTR_REFCOUNT_MAX because the count and MBE_REUSABLE_B are updated under the same buffer lock.
Leer descripción completaMostrar menos
A corrupted filesystem can violate that invariant. The syzbot reproducer reports allocator and xattr corruption before triggering this retry loop.
Check the untrusted on-disk count before incrementing it, avoiding overflow, and clear MBE_REUSABLE_B when it is already saturated. The next lookup then skips the entry that was just proven unusable. This mirrors the normal transition at EXT4_XATTR_REFCOUNT_MAX; the release path marks the entry reusable again on the exact 1024-to-1023 transition.
Using the same QEMU harness and guest parameters, current unpatched Linux hung in 6 of 8 420-second trials with the do_rmdir signature; representative NMI backtraces caught the owner spinning in ext4_xattr_block_set(). The patched kernel completed 28 of 28 trials without a hung-task report; the final twelve trials exercised the reviewed overflow-safe form of the change. syzbot's patch testing also completed without reproducing the hang.
CVSS
NVD no ha asignado puntuación CVSS a esta CVE (habitual desde el cambio de política de abril de 2026).
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.19%
- Percentil entre todas las CVEs puntuadas: 8
- 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).
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/119a2f053242ed75bdd2ebc95baf3ae7db6ccacf
- https://git.kernel.org/stable/c/4902a5cba21aeaf91e6b29e20e0967a5f6abdcd9
- https://git.kernel.org/stable/c/54b6bd40898de7906acb2bccc9a96d1b8e6b4323
- https://git.kernel.org/stable/c/55ee6533c1db7f7656fa8dd19637f3f8b8c08dc5
- https://git.kernel.org/stable/c/61631352a5b405c89be579de00903b72e6888aa4
- https://git.kernel.org/stable/c/8865cd664484517703df5c18a965dc3227572b87
- https://git.kernel.org/stable/c/889ec86464d261f026f6c334040cfc6c58c99d58
- https://git.kernel.org/stable/c/a40c45268f4358207aa9c53764fed2e05f62986a
- https://git.kernel.org/stable/c/dbd4aea175ad3c46436acb251e817b4374628072
JSON original (NVD)
Mostrar
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"vulnStatus": "Received",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: stop retrying saturated xattr cache entries\n\next4_xattr_block_set() retries when a cache entry selected for reuse\nhas a saturated reference count after taking the buffer lock. The retry\nreturns to the mbcache lookup without making that entry ineligible, so\nit can select the same unusable entry indefinitely. A task spinning\nthere can hold the parent directory's i_rwsem and leave concurrent\nrmdir callers blocked.\n\nNormally a reusable entry has a reference count below\nEXT4_XATTR_REFCOUNT_MAX because the count and MBE_REUSABLE_B are\nupdated under the same buffer lock. A corrupted filesystem can violate\nthat invariant. The syzbot reproducer reports allocator and xattr\ncorruption before triggering this retry loop.\n\nCheck the untrusted on-disk count before incrementing it, avoiding\noverflow, and clear MBE_REUSABLE_B when it is already saturated. The\nnext lookup then skips the entry that was just proven unusable. This\nmirrors the normal transition at EXT4_XATTR_REFCOUNT_MAX; the release\npath marks the entry reusable again on the exact 1024-to-1023\ntransition.\n\nUsing the same QEMU harness and guest parameters, current unpatched\nLinux hung in 6 of 8 420-second trials with the do_rmdir signature;\nrepresentative NMI backtraces caught the owner spinning in\next4_xattr_block_set(). The patched kernel completed 28 of 28 trials\nwithout a hung-task report; the final twelve trials exercised the\nreviewed overflow-safe form of the change. syzbot's patch testing also\ncompleted without reproducing the hang."
}
],
"lastModified": "2026-09-04T16:18:07.993",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}