# CVE-2021-21775: Use after free in Webkit

> A use-after-free in WebKitGTK allows attackers to leak information and potentially execute code via a malicious webpage.

- **Severity:** Medium 6.8 (`CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 7 Jul 2021
- **Updated:** 3 Aug 2024
- **Also known as:** DEBIAN-CVE-2021-21775, GHSA-ghh6-x87m-6qjh, UBUNTU-CVE-2021-21775

## What is CVE-2021-21775?

CVE-2021-21775 is a medium-severity use after free vulnerability in Debian Debian Linux, published on 7 Jul 2021. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

A use-after-free vulnerability exists in the way certain events are processed for ImageLoader objects of Webkit WebKitGTK 2.30.4. A specially crafted web page can lead to a potential information leak and further memory corruption. In order to trigger the vulnerability, a victim must be tricked into visiting a malicious webpage.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2021-21775?

It affects 3 products.


Products: Debian Debian Linux, Fedoraproject Fedora, Webkitgtk Webkitgtk.

## How do I fix CVE-2021-21775?

Upgrade to a fixed version.

## Is CVE-2021-21775 being exploited?

There is no known exploitation of CVE-2021-21775 in the wild and no public exploit code.

## 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-2021-21775 and fix it if it is affected.

What it is: CVE-2021-21775 is a medium-severity use after free vulnerability in Debian Debian Linux, published on 7 Jul 2021. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2021-21775 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-2021-21775/ (Markdown: https://insights.sbomify.com/CVE-2021-21775/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-21775
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-21775
- OSV: https://osv.dev/vulnerability/CVE-2021-21775

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-21775/
Summaries are generated and may contain mistakes; the official description above is the record.