CVE-2026-72253 netfilter: nf_conntrack_sip: validate skb_dst() before accessing it
A null pointer dereference in the Linux kernel SIP conntrack helper can cause a crash when external media is enabled on specific network subsystems.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-72253?
CVE-2026-72253 is a high-severity vulnerability in Linux, published on 15 Aug 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: nf_conntrack_sip: validate skb_dst() before accessing it
tc ingress and openvswitch do not guarantee routing information to be available. These subsystems use the conntrack helper infrastructure, and the SIP helper relies on the skb_dst() to be present if sip_external_media is set to 1 (which is disabled by default as a module parameter).
This effectively disables the sip_external_media toggle for these subsystems without resulting in a crash.
Which versions are affected by CVE-2026-72253?
How do I fix CVE-2026-72253?
Apply the vendor's patch.
Is CVE-2026-72253 being exploited?
There is no known exploitation of CVE-2026-72253 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-72253, DEBIAN-CVE-2026-72253, GHSA-7j9w-2xg9-r3v4, UBUNTU-CVE-2026-72253.