SB20260816388 - Use-after-free in Linux kernel ipv4

Description

This security bulletin contains information about 1 vulnerability.

1) Use-after-free (CVE-ID: CVE-2026-72139)

CWE-ID: CWE-416 - Use After Free

CVSSv4: 6.8 [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]

The vulnerability allows a local user to cause a denial of service.

The vulnerability exists due to use-after-free in tcp_connect() and tcp_clear_md5_list() when reconciling TCP MD5 and TCP-AO authentication state during connection setup. A local user can trigger concurrent socket operations that race with RCU readers to cause a denial of service.

The race occurs while the socket is in TCP_SYN_SENT and already present in the inet ehash, where softirq RX-path readers may access the authentication data through RCU-protected lookups.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/33a1bee413628378fd036a4f2b17ba86b0bc560c
• https://git.kernel.org/stable/c/b74cd55038905d5e74c1de109ab78a30b2ea0e1f
• https://git.kernel.org/stable/c/da48b9bf1eb95a9cfd09d615ca58cfc2b03de369