SB2026091209 - Race condition in Linux kernel btrfs

Description

This security bulletin contains information about 1 vulnerability.

1) Race condition (CVE-ID: CVE-2026-89772)

CWE-ID: CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

CVSSv4: 5.7 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N]

The vulnerability allows a local user to corrupt data or cause loss of writes.

The vulnerability exists due to missing write protection in Btrfs folio writeback handling when processing writeback for file-backed folios. A local user can modify a writable memory-mapped file during writeback to corrupt data or cause loss of writes.

The issue can affect partial-folio writeback, inline extents, folios spanning EOF, and compression processing.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/074c715e0b498891c09fe7f11e1cd9d7a04699bd
• https://git.kernel.org/stable/c/5376c9db45368eb210b4d71104ac00a59dc8b6e0