SB2026050919 - Use-after-free in Linux kernel smb server
Published: May 9, 2026
Security Bulletin ID
SB2026050919
CSH Severity
Low
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Local access
Highest impact
Denial of service
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 vulnerability.
1) Use-after-free (CVE-ID: CVE-2026-43376)
CWE-ID: CWE-416 - Use After Free
CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to a use-after-free in oplock_info handling in ksmbd when accessing oplock_info under RCU read-side critical sections. A local user can trigger concurrent access to a freed oplock_info structure to cause a denial of service.
The issue can occur when readers access oplock_info after its pointer has been cleared but before a grace period has elapsed.
Remediation
Install update from vendor's website.
References
- https://git.kernel.org/stable/c/08aa9f3c8cf4d0bee44df540dfe34e8d64069f2c
- https://git.kernel.org/stable/c/1d6abf145615dbfe267ce3b0a271f95e3780e18e
- https://git.kernel.org/stable/c/1dfd062caa165ec9d7ee0823087930f3ab8a6294
- https://git.kernel.org/stable/c/302fef75512b2c8329a3f5efab1ae7ba2562387a
- https://git.kernel.org/stable/c/ce8507ee82c888126d8e7565e27c016308d24cde