# CVE-2025-40294: Bluetooth: MGMT: Fix OOB access in parse_adv_monitor_pattern()

> A local attacker with low privileges can trigger an out-of-bounds write in the Linux kernel Bluetooth subsystem, potentially leading to code execution or privilege escalation.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 8 Dec 2025
- **Updated:** 16 Jun 2026
- **Also known as:** BELL-CVE-2025-40294, DEBIAN-CVE-2025-40294, GHSA-23g6-rffg-7f3p, ROOT-OS-DEBIAN-12-CVE-2025-40294, ROOT-OS-DEBIAN-13-CVE-2025-40294, ROOT-OS-UBUNTU-2404-CVE-2025-40294, UBUNTU-CVE-2025-40294

## What is CVE-2025-40294?

CVE-2025-40294 is a memory corruption vulnerability in Linux, published on 8 Dec 2025. 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: MGMT: Fix OOB access in parse_adv_monitor_pattern()

In the parse_adv_monitor_pattern() function, the value of
the 'length' variable is currently limited to HCI_MAX_EXT_AD_LENGTH(251).
The size of the 'value' array in the mgmt_adv_pattern structure is 31.
If the value of 'pattern[i].length' is set in the user space
and exceeds 31, the 'patterns[i].value' array can be accessed
out of bound when copied.

Increasing the size of the 'value' array in
the 'mgmt_adv_pattern' structure will break the userspace.
Considering this, and to avoid OOB access revert the limits for 'offset'
and 'length' back to the value of HCI_MAX_AD_LENGTH.

Found by InfoTeCS on behalf of Linux Verification Center
(linuxtesting.org) with SVACE.

## Which versions are affected by CVE-2025-40294?


## How do I fix CVE-2025-40294?

Apply the vendor's patch.

## Is CVE-2025-40294 being exploited?

There is no known exploitation of CVE-2025-40294 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-40294 and fix it if it is affected.

What it is: CVE-2025-40294 is a memory corruption vulnerability in Linux, published on 8 Dec 2025. 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-2025-40294 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-2025-40294/ (Markdown: https://insights.sbomify.com/CVE-2025-40294/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-40294
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-40294
- OSV: https://osv.dev/vulnerability/CVE-2025-40294

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-40294/
Summaries are generated and may contain mistakes; the official description above is the record.