CVE-2021-30154 Cross-site scripting in n/a

What is CVE-2021-30154?

CVE-2021-30154 is a medium-severity cross-site scripting vulnerability in Debian Debian Linux, published on 6 Apr 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

An issue was discovered in MediaWiki before 1.31.12 and 1.32.x through 1.35.x before 1.35.2. On Special:NewFiles, all the mediastatistics-header-* messages are output in HTML unescaped, leading to XSS.

Weakness: CWE-79

Which versions are affected by CVE-2021-30154?

1 open source package ship an affected version, including mediawiki. It affects 3 products.

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

How do I fix CVE-2021-30154?

Upgrade mediawiki to a fixed version for your release line: 1.31.12 or 1.35.2.

Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.

Is CVE-2021-30154 being exploited?

There is no known exploitation of CVE-2021-30154 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 BIT-mediawiki-2021-30154, DEBIAN-CVE-2021-30154, GHSA-56c6-mj2h-234g, UBUNTU-CVE-2021-30154.