SB2026091298 - Improper input validation in Linux kernel nfsd
Published: September 12, 2026
Security Bulletin ID
SB2026091298
CSH Severity
Low
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Remote access
Highest impact
Information disclosure
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 vulnerability.
1) Improper input validation (CVE-ID: CVE-2026-89687)
CWE-ID: CWE-20 - Improper input validation
CVSSv4: 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]
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.
Remediation
Install update from vendor's website.