CVE-2020-35478

Name: CVE-2020-35478
Creator: NVD / NIST
Published: 2020-12-18T08:15:15.293+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.1/10EPSS 1.35%

Last modified Jun 17, 2026

CVE-2020-35478 is a medium-severity vulnerability rated 6.1/10 on the CVSS scale. MediaWiki before 1.35.1 allows XSS via BlockLogFormatter.php. MediaWiki:blanknamespace potentially can be output as raw HTML with SCRIPT tags via LogFormatter::makePageLink(). EPSS estimates a 1.35% chance of exploitation in the next 30 days.

Description

MediaWiki before 1.35.1 allows XSS via BlockLogFormatter.php. MediaWiki:blanknamespace potentially can be output as raw HTML with SCRIPT tags via LogFormatter::makePageLink(). This affects MediaWiki 1.33.0 and later.

Metrics

CVSS 3.1

6.1/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS Probability

1.35%

68.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-79

Affected Software

Vendor	Product	Versions
Mediawiki	Mediawiki	>= 1.33.0, < 1.35.1
Fedoraproject	Fedora	33

References

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/STT5Z4A3BCXVH3WIPICWU2FP4IPIMUPC/
https://lists.wikimedia.org/pipermail/mediawiki-announce/2020-December/000268.htmlMailing List, Release Notes, Vendor Advisory
https://phabricator.wikimedia.org/T268938Exploit, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/STT5Z4A3BCXVH3WIPICWU2FP4IPIMUPC/
https://lists.wikimedia.org/pipermail/mediawiki-announce/2020-December/000268.htmlMailing List, Release Notes, Vendor Advisory
https://phabricator.wikimedia.org/T268938Exploit, Third Party Advisory

Timeline

Published: Dec 18, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-35478?

How severe is CVE-2020-35478?

CVE-2020-35478 has a CVSS score of 6.1/10 (MEDIUM severity). The EPSS model estimates a 1.35% probability of exploitation in the next 30 days.

How do I fix CVE-2020-35478?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2020-35478?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST