CVE-2020-35479 Cross-site scripting in n/a

What is CVE-2020-35479?

CVE-2020-35479 is a medium-severity cross-site scripting vulnerability in Debian Debian Linux, published on 18 Dec 2020. 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

MediaWiki before 1.35.1 allows XSS via BlockLogFormatter.php. Language::translateBlockExpiry itself does not escape in all code paths. For example, the return of Language::userTimeAndDate is is always unsafe for HTML in a month value. This affects MediaWiki 1.12.0 and later.

Weakness: CWE-79

Which versions are affected by CVE-2020-35479?

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-2020-35479?

Upgrade mediawiki to 1.35.1 or later.

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-2020-35479 being exploited?

There is no known exploitation of CVE-2020-35479 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-2020-35479, DEBIAN-CVE-2020-35479, GHSA-2m4p-pvg2-r5cw, UBUNTU-CVE-2020-35479.