Improper input validation in Linux kernel - CVE-2026-89687
Published: September 12, 2026
Vulnerability identifier: #VU149121
CSH Severity: Low
CVSS v4: 0 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-89687
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause nfsd to use a file that has not been opened.
The vulnerability exists due to improper validation of file open state in nfsd_file_do_acquire() when acquiring a file returned by dentry_create(). A remote attacker can trigger nfsd to use a file that has not been opened.
The condition requires atomic_open to report success without opening the file.
Affected software
Linux kernel
How to mitigate CVE-2026-89687
Install security update from vendor's repository.