# CVE-2021-4204: Memory corruption in kernel

> A local attacker with special privileges can crash the system or leak internal information via an out-of-bounds memory access in the Linux kernel's eBPF subsystem.

- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/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:** 24 Aug 2022
- **Updated:** 3 Aug 2024
- **Also known as:** DEBIAN-CVE-2021-4204, GHSA-5gx9-gr87-492v, ROOT-OS-DEBIAN-11-CVE-2021-4204, UBUNTU-CVE-2021-4204, USN-5219-1

## What is CVE-2021-4204?

CVE-2021-4204 is a high-severity memory corruption vulnerability in Debian Debian Linux, published on 24 Aug 2022. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

An out-of-bounds (OOB) memory access flaw was found in the Linux kernel's eBPF due to an Improper Input Validation. This flaw allows a local attacker with a special privilege to crash the system or leak internal information.

Weakness: CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer), CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2021-4204?

It affects 8 products.


Products: Debian Debian Linux, Linux kernel, Netapp H300s Firmware, Netapp H410c Firmware, Netapp H410s Firmware, Netapp H500s Firmware, Netapp H700s Firmware, Redhat Enterprise Linux.

## How do I fix CVE-2021-4204?

Apply the vendor's patch.

## Is CVE-2021-4204 being exploited?

There is no known exploitation of CVE-2021-4204 in the wild and no public exploit code.

Public exploit code:

- CVE-2021-4204: Linux Kernel eBPF Local Privilege Escalation (github_poc): https://github.com/tr3ee/CVE-2021-4204

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-4204 and fix it if it is affected.

What it is: CVE-2021-4204 is a high-severity memory corruption vulnerability in Debian Debian Linux, published on 24 Aug 2022. 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-2021-4204 in the wild and no public exploit code.

Affected product: Debian Debian 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-2021-4204/ (Markdown: https://insights.sbomify.com/CVE-2021-4204/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-4204
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-4204
- OSV: https://osv.dev/vulnerability/CVE-2021-4204

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-4204/
Summaries are generated and may contain mistakes; the official description above is the record.