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CVE-2026-89649

Vulnérabilité critique dans Linux (Linux)

CVSS 9.1 · Critique
EPSS 0.7%
Linux•Linux•Versions : 6.12.109, <=6.1.*, <=6.12.*, 5.15.221, 5.10.270, 0, 7.2.4, <2.6.34, 6.1.188, <b12b3320c81fd72ab36388fb2445fec9c3038f10, <=5.10.*, <68d541754d6cd3bb98d1fd8314f57e5eb533557d, <=6.6.*, <01e3f19c301d492e12f16b3b463ac14d7cf3ebe7, 6.6.157, 2.6.34, <=6.18.*, <1dd356310b1660215f9a3626580bf8b363ef981e, <38be2f3c41ecaba58bb92dc16603e09ba9fd64f1, <=7.2.*, <61f085cb8976c9cebc90e1a8933e4cc1ad8b0fce, <=*, <=5.15.*, 355da1eb7a1f91c276b991764e951bbcd8047599, 6.18.50, <848b80ca6b410f350d08b8ac19a00ef88223f2ea, <cb0cd79ae80476d1bc06bd9678484b6736f19588, 7.3

Description

In the Linux kernel, the following vulnerability has been resolved: ceph: bound xattr value length in __build_xattrs() __build_xattrs() decodes the MDS-supplied xattr blob one attribute at a time. For each attribute it reads a 32-bit name length, advances past the name bytes, reads a 32-bit value length, records the value pointer, and advances past the value bytes. The two length fields are read with ceph_decode_32_safe(), but the value bytes themselves are advanced over with a bare "p += len" and no ceph_decode_need() check that "len" bytes remain in the blob. For every attribute except the last, the next iteration's ceph_decode_32_safe() on the following name length implicitly verifies that the previous value did not run past the blob end. The final attribute has no successor, so its decoded value length is never checked against the blob bounds. A malicious or compromised metadata server can set the last attribute's value length larger than the bytes actually present in the blob. The blob is a dedicated kvmalloc() allocation sized to the wire length (ceph_buffer_new() in ceph_fill_inode()). __set_xattr() records the oversized length in xattr->val_len verbatim, and a later getxattr(2) runs memcpy(value, xattr->val, xattr->val_len) into a user-supplied buffer, copying bytes past the end of the allocation back to user space. Impact: a malicious metadata server discloses adjacent kernel heap bytes to a local user via getxattr(2) on a CephFS file. Add the missing ceph_decode_need() so an out-of-bounds value length on the final attribute fails the decode and returns -EIO instead of being stored.

Gravité et risque d'exploitation

CVE-2026-89649 obtient un score CVSS de 9.1/10, soit une gravité critique. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.68 %, ce qui la place devant 51.4 % des CVE référencées.

Que faire ?

  • Vérifiez si Linux (versions 6.12.109, <=6.1.*, <=6.12.*, 5.15.221, 5.10.270, 0, 7.2.4, <2.6.34, 6.1.188, <b12b3320c81fd72ab36388fb2445fec9c3038f10, <=5.10.*, <68d541754d6cd3bb98d1fd8314f57e5eb533557d, <=6.6.*, <01e3f19c301d492e12f16b3b463ac14d7cf3ebe7, 6.6.157, 2.6.34, <=6.18.*, <1dd356310b1660215f9a3626580bf8b363ef981e, <38be2f3c41ecaba58bb92dc16603e09ba9fd64f1, <=7.2.*, <61f085cb8976c9cebc90e1a8933e4cc1ad8b0fce, <=*, <=5.15.*, 355da1eb7a1f91c276b991764e951bbcd8047599, 6.18.50, <848b80ca6b410f350d08b8ac19a00ef88223f2ea, <cb0cd79ae80476d1bc06bd9678484b6736f19588, 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

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