# CVE-2024-21639: OOB Access in CefLayeredWindowUpdaterOSR::OnAllocatedSharedMemory

> An out-of-bounds read in CEF's shared memory handling allows attackers to read memory outside the sandbox boundaries.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 12 Jan 2024
- **Updated:** 1 Aug 2024
- **Also known as:** GHSA-m375-jw5x-x8mg

## What is CVE-2024-21639?

CVE-2024-21639 is a medium-severity memory corruption vulnerability in chromiumembedded cef, published on 12 Jan 2024. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

CEF (Chromium Embedded Framework ) is a simple framework for embedding Chromium-based browsers in other applications. `CefLayeredWindowUpdaterOSR::OnAllocatedSharedMemory` does not check the size of the shared memory, which leads to out-of-bounds read outside the sandbox. This vulnerability was patched in commit 1f55d2e.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2024-21639?

It affects 1 product.


Products: Chromiumembedded Chromium Embedded Framework.

## How do I fix CVE-2024-21639?

No fix has been published for CVE-2024-21639 yet. Limit exposure of the affected software until one is available.

## Is CVE-2024-21639 being exploited?

There is no known exploitation of CVE-2024-21639 in the wild and no public exploit code.

## Other vulnerabilities in chromiumembedded cef

- [CVE-2024-21640](https://insights.sbomify.com/CVE-2024-21640/): OOB Access in CefVideoConsumerOSR::OnFrameCaptured (medium 5.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-21639 and fix it if it is affected.

What it is: CVE-2024-21639 is a medium-severity memory corruption vulnerability in chromiumembedded cef, published on 12 Jan 2024. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2024-21639 in the wild and no public exploit code.

Affected product: chromiumembedded cef. 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-2024-21639/ (Markdown: https://insights.sbomify.com/CVE-2024-21639/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-21639
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-21639
- OSV: https://osv.dev/vulnerability/CVE-2024-21639

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-21639/
Summaries are generated and may contain mistakes; the official description above is the record.