Improper access control in MediaWiki - CVE-2021-30159
Published: April 12, 2021
Vulnerability identifier: #VU52027
CSH Severity: Medium
CVSS v4: 5.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N]
CVE-ID: CVE-2021-30159
CWE-ID: CWE-284
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to gain unauthorized access to otherwise restricted functionality.
The vulnerability exists due to improper access restrictions. Users can bypass intended restrictions on deleting pages in certain "fast double move" situations. MovePage::isValidMoveTarget() uses FOR UPDATE, but it's only called if Title::getArticleID() returns non-zero with no special flags. Next, MovePage::moveToInternal() will delete the page if getArticleID(READ_LATEST) is non-zero. Therefore, if the page is missing in the replica DB, isValidMove() will return true, and then moveToInternal() will unconditionally delete the page if it can be found in the master.
Affected software
MediaWiki
Gentoo Linux
mediawiki (Debian package)
Gentoo Linux
mediawiki (Debian package)
How to mitigate CVE-2021-30159
Install updates from vendor's website.
MediaWiki - addressed in versions 1.31.13, 1.35.2
mediawiki (Debian package) - update to 1:1.31.14-1~deb10u1
mediawiki (Debian package) - update to 1:1.31.14-1~deb10u1