# CVE-2026-99239: Linux kernel Bluetooth L2CAP race condition in channel connection

Source: https://junglewise.ai/threats/cve-2026-99239-in-the-linux-kernel-the-following-vulnerability-has-been-resolved  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-02. Updated: 2026-11-02  
License: CC BY 4.0 with a link back

CVE-2026-99239 · Severity: high · CVSS 7.8 · Published 2026-11-02

A race condition in the Linux kernel's Bluetooth L2CAP (Logical Link Control and Adaptation Protocol) component allows an attacker to violate a critical invariant that a channel can only be linked to a connection once. By exploiting timing between concurrent socket operations, an attacker could trigger double-linking of a channel, potentially causing memory corruption, denial of service, or code execution on systems with Bluetooth enabled.

Technologies: [Linux Kernel](https://junglewise.ai/threats/technologies/kernel). Vendors: [Linux](https://junglewise.ai/threats/vendors/linux).

## Quick answers

**Is CVE-2026-99239 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-99239 being exploited in the wild.

**How severe is CVE-2026-99239?** High severity, with a CVSS score of 7.8, published 2 November 2026.

**Which products and versions are affected?** Linux Kernel Affected versions with Bluetooth L2CAP enabled; patch released 2026-10-30.

**Is there a fix for CVE-2026-99239?** A patch was published on 2026-10-30: Fix committed by Greg Kroah-Hartman Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-99239 attacked?** It is attacked with local access or from the adjacent network, in an operating system.

**Am I affected by CVE-2026-99239?** Check whether you run Linux Kernel at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A TOCTOU (time-of-check-time-of-use) race exists between l2cap_chan_connect() and l2cap_sock_bind() where chan->state is read and written without proper synchronization. An attacker can trigger concurrent socket operations to cause __l2cap_chan_add() to be called twice on the same channel, violating the invariant that l2cap_chan may be linked to l2cap_conn at most once. The fix adds explicit checks in __l2cap_chan_add() and l2cap_chan_connect(), and adds locking in l2cap_sock_bind() to guard chan->state writes.

## Affected products

- Linux Linux kernel Affected versions with Bluetooth L2CAP enabled; patch released 2026-10-30

## Timeline

- 2026-11-02: disclosed: CVE-2026-99239 published
- 2026-10-30: patched: Fix committed by Greg Kroah-Hartman

## References

- [https://git.kernel.org/stable/c/10c705dd706aa93164ba41f2566f15206d6c178e](https://git.kernel.org/stable/c/10c705dd706aa93164ba41f2566f15206d6c178e)
- [https://git.kernel.org/stable/c/52fe88e4ef87311eee32b45c65603e7c69e75e7d](https://git.kernel.org/stable/c/52fe88e4ef87311eee32b45c65603e7c69e75e7d)

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