CVE-2026-45912

Description

In the Linux kernel, the following vulnerability has been resolved: ext4: don't cache extent during splitting extent Caching extents during the splitting process is risky, as it may result in stale extents remaining in the status tree. Moreover, in most cases, the corresponding extent block entries are likely already cached before the split happens, making caching here not particularly useful. Assume we have an unwritten extent, and then DIO writes the first half. [UUUUUUUUUUUUUUUU] on-disk extent U: unwritten extent [UUUUUUUUUUUUUUUU] extent status tree |<- ->| ----> dio write this range First, when ext4_split_extent_at() splits this extent, it truncates the existing extent and then inserts a new one. During this process, this extent status entry may be shrunk, and calls to ext4_find_extent() and ext4_cache_extents() may occur, which could potentially insert the truncated range as a hole into the extent status tree. After the split is completed, this hole is not replaced with the correct status. [UUUUUUU|UUUUUUUU] on-disk extent U: unwritten extent [UUUUUUU|HHHHHHHH] extent status tree H: hole Then, the outer calling functions will not correct this remaining hole extent either. Finally, if we perform a delayed buffer write on this latter part, it will re-insert the delayed extent and cause an error in space accounting. In adition, if the unwritten extent cache is not shrunk during the splitting, ext4_cache_extents() also conflicts with existing extents when caching extents. In the future, we will add checks when caching extents, which will trigger a warning. Therefore, Do not cache extents that are being split.

Gravité et risque d'exploitation

CVE-2026-45912 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 0.12 %, ce qui la place devant 1.9 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions <=6.1.*, <=6.12.*, <9a2b95cdaf07785e2739199037bd9c0863ccc1be, 0, <8b4b19a2f96348d70bfa306ef7d4a13b0bcbea79, 3.12, 7.0, 6.1.165, 6.12.75, 107a7bd31ac003e42c0f966aa8e5b26947de6024, <=5.10.*, <=6.6.*, <=6.19.*, <8302b5b4aacdbb378f7b1216bb2ee782b5142415, <4c2d9dac4d328244f9365b0a1fa27ec802821820, <=6.18.*, <5b1f4290453314e11cd8e15c7baa8a9b76c19b23, 6.6.128, 5.10.252, <692103feca376ae4298c92aa8828015d20f1d87b, <96007fd3c106aea773c1afae2d6f64cceb6da208, <3.12, 6.19.4, <=*, <=5.15.*, <93b2ebbbcb2e63cfc21a1946dfe91d3aa7952036, 5.15.202, 6.18.14) 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/8302b5b4aacdbb378f7b1216bb2ee782b5142415
• https://git.kernel.org/stable/c/692103feca376ae4298c92aa8828015d20f1d87b
• https://git.kernel.org/stable/c/4c2d9dac4d328244f9365b0a1fa27ec802821820
• https://git.kernel.org/stable/c/93b2ebbbcb2e63cfc21a1946dfe91d3aa7952036
• https://git.kernel.org/stable/c/96007fd3c106aea773c1afae2d6f64cceb6da208
• https://git.kernel.org/stable/c/5b1f4290453314e11cd8e15c7baa8a9b76c19b23
• https://git.kernel.org/stable/c/9a2b95cdaf07785e2739199037bd9c0863ccc1be
• https://git.kernel.org/stable/c/8b4b19a2f96348d70bfa306ef7d4a13b0bcbea79