# CVE-2024-21885: Xorg-x11-server: heap buffer overflow in xisenddevicehierarchyevent

> Heap buffer overflow in X.Org server allows remote code execution or crashes via SSH X11 forwarding.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **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:** 28 Feb 2024
- **Updated:** 6 Nov 2025
- **Also known as:** AZL-110537, AZL-35405, AZL-44142, BELL-CVE-2024-21885, DEBIAN-CVE-2024-21885, GHSA-2x93-8973-5mgq, UBUNTU-CVE-2024-21885

## What is CVE-2024-21885?

CVE-2024-21885 is a high-severity memory corruption vulnerability in Red Hat Enterprise Linux 6, published on 28 Feb 2024. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A flaw was found in X.Org server. In the XISendDeviceHierarchyEvent function, it is possible to exceed the allocated array length when certain new device IDs are added to the xXIHierarchyInfo struct. This can trigger a heap buffer overflow condition, which may lead to an application crash or remote code execution in SSH X11 forwarding environments.

Weakness: CWE-122 (Heap-based Buffer Overflow)

## Which versions are affected by CVE-2024-21885?


## How do I fix CVE-2024-21885?

Apply the vendor's patch.

## Is CVE-2024-21885 being exploited?

There is no known exploitation of CVE-2024-21885 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-21885 and fix it if it is affected.

What it is: CVE-2024-21885 is a high-severity memory corruption vulnerability in Red Hat Enterprise Linux 6, published on 28 Feb 2024. 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-2024-21885 in the wild and no public exploit code.

Affected product: Red Hat Enterprise Linux 6. 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-2024-21885/ (Markdown: https://insights.sbomify.com/CVE-2024-21885/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-21885
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-21885
- OSV: https://osv.dev/vulnerability/CVE-2024-21885

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-21885/
Summaries are generated and may contain mistakes; the official description above is the record.