CVE-2026-89713
A race condition in the Linux NFS server can let an attacker truncate append‑only files, potentially causing data loss or corruption. The flaw occurs when a client changes file size without proper permission checks, allowing a concurrent append to bypass security checks. The issue has been fixed in the kernel.
An official fix is available, so this entry is kept for 30 days and then removed automatically.
Who is affected
Linux kernel NFS server (nfsd) – any system running the NFS server component, especially those exposing append‑only files. Linux administrators running NFS services are the typical users.
Real-world impact
An attacker could truncate append‑only files, leading to data loss or corruption, and potentially disrupt services that rely on those files.
Why this severity
The CVSS score of 9.1 reflects a critical impact because the flaw allows an attacker to cause integrity and availability problems without needing any user interaction or special privileges. The vulnerability is a race condition that can be triggered remotely by sending a SETATTR request to the NFS server.
What to do about it
- 01Upgrade the Linux kernel to a version that includes the fix for CVE-2026-89713.
NVD description
Timeline
- Sep 11, 2026 · 2d agoPublishedDisclosed and added to the National Vulnerability Database.
- Sep 13, 2026 · 6h agoOfficial fix availableA vendor patch or mitigation now exists — see the remediation steps above.