CVE-2025-39764 netfilter: ctnetlink: remove refcounting in expectation dumpers

What is CVE-2025-39764?

CVE-2025-39764 is a medium-severity memory corruption vulnerability in Linux kernel, published on 11 Sep 2025. 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: ctnetlink: remove refcounting in expectation dumpers

Same pattern as previous patch: do not keep the expectation object alive via refcount, only store a cookie value and then use that as the skip hint for dump resumption.

AFAICS this has the same issue as the one resolved in the conntrack dumper, when we do if (!refcount_inc_not_zero(&exp->use))

to increment the refcount, there is a chance that exp == last, which causes a double-increment of the refcount and subsequent memory leak.

Which versions are affected by CVE-2025-39764?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2025-39764?

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-2025-39764 being exploited?

There is no known exploitation of CVE-2025-39764 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-67160, AZL-70828, BELL-CVE-2025-39764, DEBIAN-CVE-2025-39764, GHSA-rh5v-2xrc-gj9x, ROOT-OS-DEBIAN-11-CVE-2025-39764 and 5 more.