Junglewise Threat Intelligence

CVE-2026-45899: Linux Kernel ext4 stale extent cache on split failure

CVE-2026-45899 · Severity: info · Published 2026-05-27

Technologies: Linux Kernel. Vendors: Linux.

Executive brief

A vulnerability was identified in the Linux kernel's ext4 filesystem component, which is responsible for managing how data is stored on disks. When the system attempts to reorganize file data (splitting extents) and encounters an error, it may fail to clear out-of-date information from its internal memory cache. This could lead to data inconsistency or system instability, potentially affecting the reliability of stored information or causing unexpected system behavior.

Technical details

The vulnerability exists within the ext4 filesystem's extent management logic, specifically in the `ext4_split_extent_at()` function in `fs/ext4/extents.c`. When an error occurs during an extent split operation (such as -ENOSPC, -EDQUOT, or -ENOMEM), the kernel may return an error immediately without cleaning up the extent status tree. This results in stale extent entries remaining in the cache, which can lead to inconsistencies between the in-memory state and the on-disk metadata. The fix involves ensuring that `ext4_es_remove_extent()` is called to drop potentially stale extents from the cache whenever the splitting process fails. This is a local vulnerability requiring the ability to trigger filesystem operations on an ext4 partition.

Affected products

  • Linux Linux Kernel All versions prior to the fix in 2026-01-18 (e.g., 6.1, 6.6, 6.10, 6.11, 6.12)

Timeline

  • 2025-11-29: other: Patch authored by Zhang Yi
  • 2026-01-18: patched: Mainline kernel patch committed by Theodore Ts'o
  • 2026-05-27: disclosed: CVE published by NVD

References