CVE-2025-68191 udp_tunnel: use netdev_warn() instead of netdev_WARN()
A flaw in the Linux kernel UDP tunnel module causes unnecessary kernel warnings on allocation failures, potentially leading to log spam or system instability.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-68191?
CVE-2025-68191 is a denial of service vulnerability in Linux, published on 16 Dec 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
udp_tunnel: use netdev_warn() instead of netdev_WARN()
netdev_WARN() uses WARN/WARN_ON to print a backtrace along with file and line information. In this case, udp_tunnel_nic_register() returning an error is just a failed operation, not a kernel bug.
udp_tunnel_nic_register() can fail due to a memory allocation failure (kzalloc() or udp_tunnel_nic_alloc()). This is a normal runtime error and not a kernel bug.
Replace netdev_WARN() with netdev_warn() accordingly.
Which versions are affected by CVE-2025-68191?
How do I fix CVE-2025-68191?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2025-68191 being exploited?
There is no known exploitation of CVE-2025-68191 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2025-68191, DEBIAN-CVE-2025-68191, GHSA-wpgr-4vvj-xp76, ROOT-OS-DEBIAN-12-CVE-2025-68191, ROOT-OS-DEBIAN-13-CVE-2025-68191, ROOT-OS-UBUNTU-2204-CVE-2025-68191 and 2 more.