CVE-2026-31407 netfilter: conntrack: add missing netlink policy validations
An attacker can trigger out-of-bounds memory access in the Linux kernel netfilter subsystem, potentially leading to information disclosure or system crashes.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-31407?
CVE-2026-31407 is a high-severity memory corruption vulnerability in Linux kernel, published on 6 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
netfilter: conntrack: add missing netlink policy validations
Hyunwoo Kim reports out-of-bounds access in sctp and ctnetlink.
These attributes are used by the kernel without any validation. Extend the netlink policies accordingly.
Quoting the reporter: nlattr_to_sctp() assigns the user-supplied CTA_PROTOINFO_SCTP_STATE value directly to ct->proto.sctp.state without checking that it is within the valid range. [..]
and: ... with exp->dir = 100, the access at ct->master->tuplehash[100] reads 5600 bytes past the start of a 320-byte nf_conn object, causing a slab-out-of-bounds read confirmed by UBSAN.
Which versions are affected by CVE-2026-31407?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-31407?
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-2026-31407 being exploited?
There is no known exploitation of CVE-2026-31407 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-81866, BELL-CVE-2026-31407, DEBIAN-CVE-2026-31407, GHSA-cf8w-8g67-48gv, ROOT-OS-DEBIAN-11-CVE-2026-31407, ROOT-OS-DEBIAN-12-CVE-2026-31407 and 4 more.