CVE-2026-45912

/// Technical 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 re

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References