Out-of-bounds write in Linux kernel - CVE-2026-89674
Published: September 12, 2026
Vulnerability identifier: #VU149124
CSH Severity: Medium
CVSS v4: 6.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-89674
CWE-ID: CWE-787
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to write beyond the reserved XDR buffer or disclose uninitialized kernel memory.
The vulnerability exists due to an incorrect XDR buffer size calculation in nfsd4_ff_encode_layoutget() when encoding layoutget responses with short user or group strings and an odd-sized file handle. A remote attacker can request a layoutget operation to write beyond the reserved XDR buffer or disclose uninitialized kernel memory.
Affected software
Linux kernel
How to mitigate CVE-2026-89674
Install security update from vendor's repository.