CVE-2026-31418 netfilter: ipset: drop logically empty buckets in mtype_del

What is CVE-2026-31418?

CVE-2026-31418 is a medium-severity denial of service vulnerability in Linux kernel, published on 13 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: ipset: drop logically empty buckets in mtype_del

mtype_del() counts empty slots below n->pos in k, but it only drops the bucket when both n->pos and k are zero. This misses buckets whose live entries have all been removed while n->pos still points past deleted slots.

Treat a bucket as empty when all positions below n->pos are unused and release it directly instead of shrinking it further.

Which versions are affected by CVE-2026-31418?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-31418?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2026-31418 being exploited?

There is no known exploitation of CVE-2026-31418 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as AZL-82727, BELL-CVE-2026-31418, DEBIAN-CVE-2026-31418, GHSA-vwvf-62c8-j66c, ROOT-OS-DEBIAN-11-CVE-2026-31418, ROOT-OS-DEBIAN-12-CVE-2026-31418 and 4 more.