Bug 1909240 (CVE-2020-35480)

Summary: CVE-2020-35480 mediawiki: divergent behavior for contributions and user pages of hidden users and missing users
Product: [Other] Security Response Reporter: Guilherme de Almeida Suckevicz <gsuckevi>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED WONTFIX QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: aos-bugs, axel.thimm, bmontgom, eparis, jburrell, jokerman, mike, nstielau, puiterwijk, shurley, sponnaga
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: mediawiki 1.31.11, mediawiki 1.35.1 Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2021-10-28 02:59:20 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 1909241, 1910209    
Bug Blocks: 1909242    

Description Guilherme de Almeida Suckevicz 2020-12-18 17:16:14 UTC 
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.

References:
https://phabricator.wikimedia.org/T120883
https://lists.wikimedia.org/pipermail/mediawiki-announce/2020-December/000268.html
Comment 1 Guilherme de Almeida Suckevicz 2020-12-18 17:16:29 UTC 
Created mediawiki tracking bugs for this issue:

Affects: fedora-all [bug 1909241]
Comment 3 Sam Fowler 2020-12-23 06:25:44 UTC 
External References:

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