SB20260812372 - Use-after-free in Linux kernel mptcp

Description

This security bulletin contains information about 1 vulnerability.

1) Use-after-free (CVE-ID: CVE-2026-68170)

CWE-ID: CWE-416 - Use After Free

CVSSv4: 8.5 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]

The vulnerability allows a local user to cause a denial of service or execute arbitrary code.

The vulnerability exists due to a use-after-free in mptcp_backlog_purge() and backlog handling in net/mptcp/protocol.c when closing an MPTCP subflow during concurrent softirq RX processing. A local user can trigger concurrent subflow close and backlog processing to cause a denial of service or execute arbitrary code.

The issue occurs because backlog cleanup for a closing subflow was performed without proper serialization under mptcp_data_lock(), which could leave skb->sk referencing a freed subflow socket.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/625fc6060864889fe3d370cdeffbbab762af3cb4
• https://git.kernel.org/stable/c/bd7aae448f6ee9d82599a4474664de1e6e91a535