CVE-2025-40133: mptcp: Use __sk_dst_get() and dst_dev_rcu() in mptcp_active_enable().

Severity: high (CVSS 8.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-11-12 · updated 2026-10-19

Description

In the Linux kernel, the following vulnerability has been resolved: mptcp: Use __sk_dst_get() and dst_dev_rcu() in mptcp_active_enable(). mptcp_active_enable() is called from subflow_finish_connect(), which is icsk->icsk_af_ops->sk_rx_dst_set() and it's not always under RCU. Using sk_dst_get(sk)->dev could trigger UAF. Let's use __sk_dst_get() and dst_dev_rcu().

Affected products

Linux kernel: 6.12 — fixed in 6.18

How to fix

Upgrade to a fixed version: Linux kernel 6.18. Check the vendor advisory for mitigations.

References

https://git.kernel.org/stable/c/893c49a78d9f85e4b8081b908fb7c407d018106a
https://git.kernel.org/stable/c/ad16235c9d3ef7ec17c109ff39b7504f49d17072
https://git.kernel.org/stable/c/cc976ec9e38bb79409de3261ba1dbb6868e2a53e

Get alerted when CVE-2025-40133 or the next vulnerability affects your stack