SB20260917131 - Improper update of reference count in Linux kernel f2fs
Published: September 17, 2026
Security Bulletin ID
SB20260917131
CSH Severity
Low
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Local access
Highest impact
Code execution
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 vulnerability.
1) Improper update of reference count (CVE-ID: CVE-2026-89841)
CWE-ID: CWE-911 - Improper Update of Reference Count
CVSSv4: 8.5 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to improper reference count handling in the f2fs redirty_blocks() function when a folio fails to be pinned. A local user can trigger block redirtying to cause a denial of service.
The issue requires the failed folio to have already been populated in the page cache by readahead.
Remediation
Install update from vendor's website.