CVE-2023-52924 netfilter: nf_tables: don't skip expired elements during walk

What is CVE-2023-52924?

CVE-2023-52924 is a medium-severity memory corruption vulnerability in Linux kernel, published on 5 Feb 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: nf_tables: don't skip expired elements during walk

There is an asymmetry between commit/abort and preparation phase if the following conditions are met:

1. set is a verdict map ("1.2.3.4 : jump foo") 2. timeouts are enabled

In this case, following sequence is problematic:

1. element E in set S refers to chain C 2. userspace requests removal of set S 3. kernel does a set walk to decrement chain->use count for all elements from preparation phase 4. kernel does another set walk to remove elements from the commit phase (or another walk to do a chain->use increment for all elements from abort phase)

If E has already expired in 1), it will be ignored during list walk, so its use count won't have been changed.

Then, when set is culled, ->destroy callback will zap the element via nf_tables_set_elem_destroy(), but this function is only safe for elements that have been deactivated earlier from the preparation phase: lack of earlier deactivate removes the element but leaks the chain use count, which results in a WARN splat when the chain gets removed later, plus a leak of the nft_chain structure.

Update pipapo_get() not to skip expired elements, otherwise flush command reports bogus ENOENT errors.

Which versions are affected by CVE-2023-52924?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2023-52924?

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-2023-52924 being exploited?

There is no known exploitation of CVE-2023-52924 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 BELL-CVE-2023-52924, DEBIAN-CVE-2023-52924, GHSA-4rw8-6238-r9gq, UBUNTU-CVE-2023-52924.