CVE-2026-80808
Vulnérabilité non évaluée dans Linux (Linux)
Description
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. 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.
Gravité et risque d'exploitation
CVE-2026-80808 obtient un score CVSS de 0.0/10, soit une gravité non évaluée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.19 %, ce qui la place devant 8.7 % des CVE référencées.
Que faire ?
- Vérifiez si Linux (versions 7.2.1, 6.1.185, <=6.1.*, 7.1.11, <=6.12.*, 1be97463696c7291a3e1547614e96432b0bd3add, 6.12.106, 0, c6fac5cf5a5098732623bcd00a8a3eb9f5465144, <54b6bd40898de7906acb2bccc9a96d1b8e6b4323, 1a56cd972ce121b6cf2517a47a578782bbd2ec95, 5.10.267, <=7.1.*, 5.19.2, 6.6.154, 4.19.270, <4.20, <=5.10.*, <=6.6.*, <4902a5cba21aeaf91e6b29e20e0967a5f6abdcd9, 6.0, 5.4.229, <6.0, <5.15.218, <61631352a5b405c89be579de00903b72e6888aa4, af8ecc8d20e72130771cc076bce7fcf17ccda6c4, <5.5, <=6.18.*, <8865cd664484517703df5c18a965dc3227572b87, 5.15.61, 6.18.47, <5.20, <=7.2.*, 96fa141fa295ae9428da73c56c9852053b575c04, 98953044b3cdb2cb7d82e7365b659e2ed4f4ca4d, <5.19, 65f8b80053a1b2fd602daa6814e62d6fa90e5e9b, 5.18.18, <119a2f053242ed75bdd2ebc95baf3ae7db6ccacf, 5.10.163, <=*, <5.10.267, <a40c45268f4358207aa9c53764fed2e05f62986a, <=5.15.*, <dbd4aea175ad3c46436acb251e817b4374628072, <55ee6533c1db7f7656fa8dd19637f3f8b8c08dc5, <889ec86464d261f026f6c334040cfc6c58c99d58, 5.15.218, 7.3) est présent sur votre parc.
- Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
- À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
- Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.
Références
- https://git.kernel.org/stable/c/119a2f053242ed75bdd2ebc95baf3ae7db6ccacf
- https://git.kernel.org/stable/c/61631352a5b405c89be579de00903b72e6888aa4
- https://git.kernel.org/stable/c/8865cd664484517703df5c18a965dc3227572b87
- https://git.kernel.org/stable/c/a40c45268f4358207aa9c53764fed2e05f62986a
- https://git.kernel.org/stable/c/889ec86464d261f026f6c334040cfc6c58c99d58
- https://git.kernel.org/stable/c/4902a5cba21aeaf91e6b29e20e0967a5f6abdcd9
- https://git.kernel.org/stable/c/55ee6533c1db7f7656fa8dd19637f3f8b8c08dc5
- https://git.kernel.org/stable/c/dbd4aea175ad3c46436acb251e817b4374628072
- https://git.kernel.org/stable/c/54b6bd40898de7906acb2bccc9a96d1b8e6b4323