CVE-2026-23083 fou: Don't allow 0 for FOU_ATTR_IPPROTO.
A missing check in the Linux kernel's FOU module allows a null pointer dereference, leading to a denial of service.
- 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-2026-23083?
CVE-2026-23083 is a high-severity vulnerability in Linux kernel, published on 4 Feb 2026. 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:
fou: Don't allow 0 for FOU_ATTR_IPPROTO.
fou_udp_recv() has the same problem mentioned in the previous patch.
If FOU_ATTR_IPPROTO is set to 0, skb is not freed by fou_udp_recv() nor "resubmit"-ted in ip_protocol_deliver_rcu().
Let's forbid 0 for FOU_ATTR_IPPROTO.
Weakness: CWE-20
Which versions are affected by CVE-2026-23083?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-23083?
Apply the vendor's patch.
Is CVE-2026-23083 being exploited?
There is no known exploitation of CVE-2026-23083 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-77202, BELL-CVE-2026-23083, DEBIAN-CVE-2026-23083, GHSA-v7qx-38vp-6jx8, ROOT-OS-UBUNTU-2204-CVE-2026-23083, ROOT-OS-UBUNTU-2404-CVE-2026-23083 and 1 more.