# CVE-2026-74540: Bluetooth: L2CAP: fix UAF in l2cap_le_connect_rsp

> A use-after-free in the Linux kernel Bluetooth L2CAP handler allows attackers to potentially execute code or escalate privileges via concurrent channel operations.

- **Severity:** High 8.8 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Aug 2026
- **Updated:** 16 Oct 2026
- **Also known as:** AZL-96479, BELL-CVE-2026-74540, DEBIAN-CVE-2026-74540, GHSA-j62w-h52r-54ch, UBUNTU-CVE-2026-74540

## What is CVE-2026-74540?

CVE-2026-74540 is a high-severity use after free vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: L2CAP: fix UAF in l2cap_le_connect_rsp

l2cap_le_connect_rsp() obtains a channel via
__l2cap_get_chan_by_ident() but neither holds a reference nor uses
l2cap_chan_hold_unless_zero() before locking and operating on it.
A concurrent l2cap_chan_del() triggered by a remote disconnect can
free the channel between the lookup and l2cap_chan_lock(), causing
a use-after-free.

The BR/EDR counterpart l2cap_connect_rsp() and the sibling handler
l2cap_le_command_rej() already use l2cap_chan_hold_unless_zero()
to safely hold a reference, but l2cap_le_connect_rsp() was left
unprotected.

Fix by adding l2cap_chan_hold_unless_zero() after the ident lookup
and l2cap_chan_put() on the exit path, consistent with other L2CAP
response handlers.

## Which versions are affected by CVE-2026-74540?


## How do I fix CVE-2026-74540?

Apply the vendor's patch.

## Is CVE-2026-74540 being exploited?

There is no known exploitation of CVE-2026-74540 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74540 and fix it if it is affected.

What it is: CVE-2026-74540 is a high-severity use after free vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-74540 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-74540/ (Markdown: https://insights.sbomify.com/CVE-2026-74540/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74540
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74540
- OSV: https://osv.dev/vulnerability/CVE-2026-74540

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74540/
Summaries are generated and may contain mistakes; the official description above is the record.