SB20260502152 - Time-of-check Time-of-use (TOCTOU) Race Condition in Linux kernel packet
Published: May 2, 2026
Security Bulletin ID
SB20260502152
CSH Severity
Low
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Local access
Highest impact
Data manipulation
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 security vulnerability.
1) Time-of-check Time-of-use (TOCTOU) Race Condition (CVE-ID: CVE-2026-31700)
The vulnerability allows a local user to bypass safety checks.
The vulnerability exists due to a time-of-check time-of-use race condition in tpacket_snd() when processing a mmap'd vnet_hdr in the TPACKET TX path with PACKET_VNET_HDR enabled. A local user can modify vnet_hdr fields in the shared ring buffer between validation and use to bypass safety checks.
Only the TPACKET TX path is affected.
Remediation
Install update from vendor's website.
References
- https://git.kernel.org/stable/c/28324a3b62d9ce7f9bdd65a8ce63f382041d1b27
- https://git.kernel.org/stable/c/2c054e17d9d41f1020376806c7f750834ced4dc5
- https://git.kernel.org/stable/c/3a1bf9116ea31470b89692585c3910dfe830dcdd
- https://git.kernel.org/stable/c/48a6ef291a17639e1b6ae0fbe9c8b2bb87d7804b
- https://git.kernel.org/stable/c/74e2db36fe50e3ad9d5300d7fd0e6e2a15a6d121