CVE-2026-72348 netfilter: ip6tables: mark malformed IPv6 extension headers for hotdrop
Attackers can bypass ip6tables drop rules by sending malformed IPv6 extension headers, allowing unauthorized network traffic.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-72348?
CVE-2026-72348 is a critical 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: ip6tables: mark malformed IPv6 extension headers for hotdrop
The ah, hbh and rt matches check that the fixed extension header is present, then use the header length field to derive the advertised extension header length for matching.
For the ah match, add the missing advertised-length check. For hbh and rt, update the existing advertised-length checks. In all three cases, set hotdrop to true before returning false when the advertised extension header length exceeds the available skb data.
Returning false treats the packet as a rule mismatch. Set hotdrop to true and drop malformed packets so they cannot bypass rules intended to drop packets with these IPv6 extension headers.
Which versions are affected by CVE-2026-72348?
How do I fix CVE-2026-72348?
Apply the vendor's patch.
Is CVE-2026-72348 being exploited?
There is no known exploitation of CVE-2026-72348 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-72348, DEBIAN-CVE-2026-72348, GHSA-mf85-825j-jwwx, UBUNTU-CVE-2026-72348.