CVE-2026-89723

Description

In the Linux kernel, the following vulnerability has been resolved: nilfs2: fix slab-out-of-bounds in nilfs_direct_propagate after truncation Shuangpeng Bai reported that KASAN detected a slab-out-of-bounds error in nilfs_direct_propagate() during testing. Analysis revealed that after truncating a file, a node block immediately below the B-tree root was not deleted. Instead, it remained in the B-tree node cache in a dirty state. The log writer subsequently detected this block and incorrectly invoked nilfs_direct_propagate() on it, which is designed to handle only data blocks in direct mapping. B-tree nodes in the cache are managed by virtual block numbers, and their logical keys typically exceed the range expected by direct mapping. Consequently, processing such a node as a direct mapping entry triggers a slab-out-of-bounds access. The root cause is that when a B-tree mapping collapses into a direct mapping during truncation, an intermediate node block pointed to by the root node is left behind as garbage instead of being explicitly deleted. This resolves the issue by adding a nilfs_btree_discard() operation to delete the remaining intermediate node block during the conversion. A 'deform' flag is added to the bop_delete interface to explicitly signal that the deletion is part of a mapping transformation. This allows the B-tree mapping implementation to perform the necessary cleanup and discarding of the residual node structure that would be otherwise be left orphaned after the transition.

Gravité et risque d'exploitation

CVE-2026-89723 obtient un score CVSS de 7.8/10, soit une gravité élevée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.17 %, ce qui la place devant 5.9 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions <=6.1.*, <=6.12.*, 5.15.221, <45662dedb8f272ef7f16e69f13424c4bd0399240, 5.10.270, 0, 7.2.4, <4a1bb1f9f24a935c9b3f4fbf98012fa6d4ad826d, 6.1.188, <448636c745a3f3b8582a0b8ce718c890a11c0fa9, <39005fd1ce654ffdecacddc406b9a038efe606e6, <=5.10.*, 2.6.30, <=6.6.*, <bf49e6f6ddc12445a0330708b365de6458085980, 36a580eb489f54d81a0534974962e732a314b999, 6.6.157, <2.6.30, <=6.18.*, <=7.2.*, <5d3783c451a546373662ee11ec17019273e68034, <=*, <=5.15.*, 6.18.50, 6.12.109, <28362e8ce51377afdec1782e661e808328a10514, <b313edfbc0c2a60f7ce09b2e81ee71909ab8ddaf, 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/39005fd1ce654ffdecacddc406b9a038efe606e6
• https://git.kernel.org/stable/c/bf49e6f6ddc12445a0330708b365de6458085980
• https://git.kernel.org/stable/c/4a1bb1f9f24a935c9b3f4fbf98012fa6d4ad826d
• https://git.kernel.org/stable/c/b313edfbc0c2a60f7ce09b2e81ee71909ab8ddaf
• https://git.kernel.org/stable/c/5d3783c451a546373662ee11ec17019273e68034
• https://git.kernel.org/stable/c/448636c745a3f3b8582a0b8ce718c890a11c0fa9
• https://git.kernel.org/stable/c/28362e8ce51377afdec1782e661e808328a10514
• https://git.kernel.org/stable/c/45662dedb8f272ef7f16e69f13424c4bd0399240