CVE-2026-23455 netfilter: nf_conntrack_h323: check for zero length in DecodeQ931()
A missing length check in the Linux kernel's H.323 conntrack module allows out-of-bounds reads, potentially causing crashes or information disclosure.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-23455?
CVE-2026-23455 is a critical memory corruption vulnerability in Linux kernel, published on 3 Apr 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_h323: check for zero length in DecodeQ931()
In DecodeQ931(), the UserUserIE code path reads a 16-bit length from the packet, then decrements it by 1 to skip the protocol discriminator byte before passing it to DecodeH323_UserInformation(). If the encoded length is 0, the decrement wraps to -1, which is then passed as a large value to the decoder, leading to an out-of-bounds read.
Add a check to ensure len is positive after the decrement.
Weakness: CWE-125
Which versions are affected by CVE-2026-23455?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-23455?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-23455 being exploited?
There is no known exploitation of CVE-2026-23455 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-23455, DEBIAN-CVE-2026-23455, GHSA-gm78-p64f-gx97, ROOT-OS-DEBIAN-11-CVE-2026-23455, ROOT-OS-DEBIAN-12-CVE-2026-23455, ROOT-OS-DEBIAN-13-CVE-2026-23455 and 3 more.