includes/User.php in MediaWiki before 1.16.5, when wgBlockDisablesLogin is enabled, does not clear certain cached data after verification of an auth token fails, which allows remote attackers to bypass authentication by creating crafted wikiUserID and wikiUserName cookies, or by leveraging an unattended workstation.

The remote host is affected by the vulnerability described in GLSA-201206-09 (MediaWiki: Multiple vulnerabilities)

    Multiple vulnerabilities have been discovered in mediawiki. Please       review the CVE identifiers referenced below for details.
  Impact :

    MediaWiki allows remote attackers to bypass authentication, to perform       imports from any wgImportSources wiki via a crafted POST request, to       conduct cross-site scripting (XSS) attacks or obtain sensitive       information, to inject arbitrary web script or HTML, to conduct       clickjacking attacks, to execute arbitrary PHP code, to inject arbitrary       web script or HTML, to bypass intended access restrictions and to obtain       sensitive information.
  Workaround :

    There is no known workaround at this time.

MediaWiki 1.16.5 was released to correct two security flaws :

The first issue is yet another recurrence of the Internet Explorer 6 XSS vulnerability that caused the release of 1.16.4. It was pointed out that there are dangerous extensions with more than four characters, so the regular expressions we introduced had to be updated to match longer extensions. (CVE-2011-1765)

The second issue allows unauthenticated users to gain additional rights, on wikis where $wgBlockDisablesLogin is enabled. By default, it is disabled. The issue occurs when a malicious user sends cookies which contain the user name and user ID of a 'victim' account. In certain circumstances, the rights of the victim are loaded and persist throughout the malicious request, allowing the malicious user to perform actions with the victim's rights. (CVE-2011-1766)

$wgBlockDisablesLogin is a feature which is sometimes used on private wikis to prevent users who have an account from logging in and viewing content on the wiki.

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

ID	Name	Product	Family	Severity
59647	GLSA-201206-09 : MediaWiki: Multiple vulnerabilities	Nessus	Gentoo Local Security Checks	high
54609	Fedora 13 : mediawiki-1.16.5-59.fc13 (2011-6775)	Nessus	Fedora Local Security Checks	medium
54608	Fedora 14 : mediawiki-1.16.5-59.fc14 (2011-6774)	Nessus	Fedora Local Security Checks	medium
54572	Fedora 15 : mediawiki-1.16.5-59.fc15 (2011-6781)	Nessus	Fedora Local Security Checks	medium

Detections

Analytics

CVE-2011-1766

critical

Tenable Plugins

high

medium

medium

medium