CVE-2021-21779 Use after free in Webkit

What is CVE-2021-21779?

CVE-2021-21779 is a medium-severity use after free vulnerability in Debian Debian Linux, published on 8 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 Webkit’s GraphicsContext handles certain events in WebKitGTK 2.30.4. A specially crafted web page can lead to a potential information leak and further memory corruption. A victim must be tricked into visiting a malicious web page to trigger this vulnerability.

Weakness: CWE-416

Which versions are affected by CVE-2021-21779?

It affects 3 products.

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

How do I fix CVE-2021-21779?

Upgrade to a fixed version.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is CVE-2021-21779 being exploited?

There is no known exploitation of CVE-2021-21779 in the wild and no public exploit code.

Other vulnerabilities in Debian Debian Linux

• CVE-2015-3306 ProFTPD Improper Access Control Exploited Critical 10.0
• CVE-2025-49113 RoundCube Webmail Deserialization of Untrusted Data Exploited Critical 9.9
• CVE-2026-24061 GNU InetUtils Argument Injection Exploited Critical 9.8
• CVE-2025-39682 Linux Kernel Improper Check for Unusual or Exceptional Conditions Exploited Critical 9.8
• CVE-2024-9680 Mozilla Firefox Use-After-Free Exploited Critical 9.8

All Debian Debian Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2021-21779, GHSA-fvf7-58x3-4492, UBUNTU-CVE-2021-21779.