CVE-2025-40170 net: use dst_dev_rcu() in sk_setup_caps()
A race condition in Linux kernel networking allows attackers to cause a denial of service via improper RCU protection of device pointers.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-40170?
CVE-2025-40170 is a high-severity vulnerability in Linux, published on 12 Nov 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
net: use dst_dev_rcu() in sk_setup_caps()
Use RCU to protect accesses to dst->dev from sk_setup_caps() and sk_dst_gso_max_size().
Also use dst_dev_rcu() in ip6_dst_mtu_maybe_forward(), and ip_dst_mtu_maybe_forward().
ip4_dst_hoplimit() can use dst_dev_net_rcu().
Which versions are affected by CVE-2025-40170?
How do I fix CVE-2025-40170?
Apply the vendor's patch.
Is CVE-2025-40170 being exploited?
There is no known exploitation of CVE-2025-40170 in the wild and no public exploit code.
Sources
Also known as AZL-70022, BELL-CVE-2025-40170, DEBIAN-CVE-2025-40170, GHSA-3vr4-gx8q-4fgg, ROOT-OS-DEBIAN-11-CVE-2025-40170, ROOT-OS-DEBIAN-12-CVE-2025-40170 and 4 more.