SB2026091273 - Time-of-check Time-of-use (TOCTOU) Race Condition in Linux kernel nfsd
Published: September 12, 2026
Security Bulletin ID
SB2026091273
CSH Severity
Medium
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Remote access
Highest impact
Data manipulation
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 vulnerability.
1) Time-of-check Time-of-use (TOCTOU) Race Condition (CVE-ID: CVE-2026-89713)
CWE-ID: CWE-367 - Time-of-check Time-of-use (TOCTOU) Race Condition
CVSSv4: 6 [CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote user to truncate append-only files.
The vulnerability exists due to a time-of-check to time-of-use race condition in nfsd_setattr() when handling SETATTR size updates for append-only files. A remote user can issue a SETATTR request that races with a concurrent append to truncate append-only files.
Remediation
Install update from vendor's website.