CVE-2026-74564 netfilter: xt_hashlimit: validate hashtable supports XT_HASHLIMIT_RATE_MATCH
A missing validation in the Linux kernel netfilter hashlimit module allows uninitialized memory access, potentially causing a system crash.
- 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-2026-74564?
CVE-2026-74564 is a high-severity vulnerability in Linux, published on 15 Aug 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: xt_hashlimit: validate hashtable supports XT_HASHLIMIT_RATE_MATCH
The XT_HASHLIMIT_RATE_MATCH flag mode changes the semantics of the dsthash_ent structure which represents an entry in the hashtable. There is a union area which uses a different layout to express the rate match mode.
Update .checkentry path to validate the XT_HASHLIMIT_RATE_MATCH mode flag is requested by two or more different rules that refer to the same hashtable. Otherwise, uninitialized access to the burst field in the union is possible.
Reject the use of the XT_HASHLIMIT_RATE_MATCH mode flag if set on by revision less than 3 too.
Which versions are affected by CVE-2026-74564?
How do I fix CVE-2026-74564?
Apply the vendor's patch.
Is CVE-2026-74564 being exploited?
There is no known exploitation of CVE-2026-74564 in the wild and no public exploit code.
Sources
Also known as AZL-96564, BELL-CVE-2026-74564, DEBIAN-CVE-2026-74564, GHSA-mhj7-jjgw-7gmc, UBUNTU-CVE-2026-74564.