An issue was discovered in MediaWiki before 1.35.1. Missing users (accounts that don't exist) and hidden users (accounts that have been explicitly hidden due to being abusive, or similar) that the viewer cannot see are handled differently, exposing sensitive information about the hidden status to unprivileged viewers. This exists on various code paths.

https://lists.wikimedia.org/pipermail/mediawiki-announce/2020-December /000268.html

Note that Tenable Network Security has extracted the preceding description block directly from the Fedora update system website.
Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

Multiple security issues were discovered in MediaWiki, a website engine for collaborative work.

CVE-2020-15005

Private wikis behind a caching server using the img_auth.php image authorization security feature may have had their files cached publicly, so any unauthorized user could view them.

CVE-2020-35477

Blocks legitimate attempts to hide log entries in some situations.

CVE-2020-35479

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.

CVE-2020-35480

Missing users (accounts that don't exist) and hidden users (accounts that have been explicitly hidden due to being abusive, or similar) that the viewer cannot see are handled differently, exposing sensitive information about the hidden status to unprivileged viewers.

For Debian 9 stretch, these problems have been fixed in version 1:1.27.7-1~deb9u7.

We recommend that you upgrade your mediawiki packages.

For the detailed security status of mediawiki please refer to its security tracker page at:
https://security-tracker.debian.org/tracker/mediawiki

NOTE: Tenable Network Security has extracted the preceding description block directly from the DLA security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

Multiple security issues were discovered in MediaWiki, a website engine for collaborative work, which could result in cross-site scripting or the disclosure of hidden users.

ID	Name	Product	Family	Severity
144618	Fedora 33 : mediawiki (2020-0be2d40e13)	Nessus	Fedora Local Security Checks	high
144574	Debian DLA-2504-1 : mediawiki security update	Nessus	Debian Local Security Checks	medium
144477	Debian DSA-4816-1 : mediawiki - security update	Nessus	Debian Local Security Checks	high

Detections

Analytics

CVE-2020-35480

medium

Tenable Plugins

high

medium

high