CVE-2026-52998 netfilter: nfnetlink_osf: fix potential NULL dereference in ttl check
A NULL pointer dereference in the Linux kernel netfilter module allows attackers to cause a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-52998?
CVE-2026-52998 is a high-severity vulnerability in Linux kernel, published on 24 Jun 2026. 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:
netfilter: nfnetlink_osf: fix potential NULL dereference in ttl check
The nf_osf_ttl() function accessed skb->dev to perform a local interface address lookup without verifying that the device pointer was valid.
Additionally, the implementation utilized an in_dev_for_each_ifa_rcu loop to match the packet source address against local interface addresses. It assumed that packets from the same subnet should not see a decrement on the initial TTL. A packet might appear it is from the same subnet but it actually isn't especially in modern environments with containers and virtual switching.
Remove the device dereference and interface loop. Replace the logic with a switch statement that evaluates the TTL according to the ttl_check.
Weakness: CWE-476
Which versions are affected by CVE-2026-52998?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-52998?
Apply the vendor's patch.
Is CVE-2026-52998 being exploited?
There is no known exploitation of CVE-2026-52998 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-52998, DEBIAN-CVE-2026-52998, GHSA-pphc-92v7-v4w2, ROOT-OS-DEBIAN-11-CVE-2026-52998, ROOT-OS-DEBIAN-12-CVE-2026-52998, ROOT-OS-UBUNTU-2204-CVE-2026-52998 and 2 more.