ApiParse in MediaWiki before 1.23.15, 1.26.x before 1.26.4, and 1.27.x before 1.27.1 allows remote attackers to bypass intended per-title read restrictions via a parse action to api.php.

The version of MediaWiki installed is 1.23.x prior to 1.23.15, 1.26.x prior to 1.26.4, or 1.27.x prior to 1.27.1, and is affected by multiple vulnerabilities :

 - A flaw exists as HTTP requests to 'includes/OutputPage.php' do not require multiple steps, or explicit confirmation while utilizing predictable edit tokens. By tricking a user into following a specially crafted link, a context-dependent attacker can perform a Cross-Site Request Forgery (CSRF / XSRF) attack causing the victim to edit CSS content.
 - A flaw exists in 'includes/api/ApiParse.php' that is triggered as head items are not properly generated in the context of the title. This may allow a remote attacker to have an unspecified impact.
 - A flaw exists that allows a stored cross-site scripting (XSS) attack. This flaw exists because the 'includes/parser/Parser.php' script does not validate input to unclosed internal links before returning it to users. This may allow a remote attacker to create a specially crafted request that would execute arbitrary script code in a user's browser session within the trust relationship between their browser and the server.
 - A flaw exists that allows a XSS attack. This flaw exists because the 'Html:inlineStyle()' function in 'includes/Html.php' does not validate input when handling improper inline style blocks via the CSS user subpage preview feature before returning it to users. This may allow a remote attacker to create a specially crafted request that would execute arbitrary script code in a user's browser session within the trust relationship between their browser and the server.
 - A flaw exists in the 'includes/filerepo/file/LocalFile.php' script that may allow an authenticated remote attacker to bypass suppressed viewing restrictions by deleting a file and then undeleting a specific revision of it.
 - A flaw exists that is due to the program failing to timeout a user's session after they have been blocked. This may allow a remote attacker to bypass block features.
 - A flaw exists in the 'includes/user/User.php' script that is triggered during the handling of extension hook functions. This may allow a remote attacker to bypass permission restrictions.
 - A flaw exists in the 'includes/api/ApiParse.php' script that is triggered as read permissions are not properly checked when loading page content. This may allow a remote attacker to gain access to sensitive information and bypass the 'Lockdown' extension.

https://www.mediawiki.org/wiki/MediaWiki_1.27

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.

https://www.mediawiki.org/wiki/Release_notes/1.26#MediaWiki_1.26.4

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.

According to its version number, the MediaWiki application running on the remote web server is 1.23.x prior to 1.23.15, 1.26.x prior to 1.26.4, or 1.27.x prior to 1.27.1. It is, therefore, affected by the following vulnerabilities :

  - An information disclosure vulnerability exists in the     ApiParse.php script due to improper checking of read     permissions when loading page content. An     unauthenticated, remote attacker can exploit this to     disclose sensitive information. (CVE-2016-6331)

  - A security bypass vulnerability exists due to a failure     to timeout a user's session after it has been blocked.
    An authenticated, remote attacker can exploit this to     bypass block features. (CVE-2016-6332)

  - A cross-site request forgery vulnerability (XSRF) exists     in the OutputPage.php script due to a failure to require     multiple steps, explicit confirmation, or a unique token     when performing certain sensitive actions. An     unauthenticated, remote attacker can exploit this, by     convincing a user to follow a specially crafted link, to     perform arbitrary edits to CSS content. (CVE-2016-6333)

  - A cross-site scripting (XSS) vulnerability exists in the     Html.php script due to improper validation of     user-supplied input when handling improper inline style     blocks via the CSS user subpage preview feature. An     unauthenticated, remote attacker can exploit this, via a     specially crafted request, to execute arbitrary script     code in a user's browser session. (CVE-2016-6333)

  - A cross-site scripting (XSS) vulnerability exists in the     Parser.php script due to improper validation of input to     unclosed internal links. An unauthenticated, remote     attacker can exploit this, via a specially crafted     request, to execute arbitrary script code in a user's     browser session. (CVE-2016-6334)

  - A flaw exists in the ApiParse.php script due to head     items not being properly generated in the context of a     title. An unauthenticated, remote attacker can exploit     this to have an unspecified impact. (CVE-2016-6335)

  - A flaw exists in the LocalFile.php script that allows an     authenticated, remote attacker to bypass suppressed     viewing restrictions by deleting a file and then     undeleting a specific revision of it. (CVE-2016-6336)

  - A security bypass vulnerability exists in the User.php     script due to improper handling of extension hook     functions. An unauthenticated, remote attacker can     exploit this to bypass permission restrictions. Note     that this vulnerability affects 1.27.x only.
    (CVE-2016-6337)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

ID	Name	Product	Family	Severity
9824	MediaWiki 1.23.x < 1.23.15 / 1.26.x < 1.26.4 / 1.27.x < 1.27.1 Multiple Vulnerabilities	Nessus Network Monitor	CGI	critical
94835	Fedora 25 : mediawiki (2016-9299ce1c7d)	Nessus	Fedora Local Security Checks	high
93358	Fedora 23 : mediawiki (2016-ce1678471e)	Nessus	Fedora Local Security Checks	high
93356	Fedora 24 : mediawiki (2016-af3b0af887)	Nessus	Fedora Local Security Checks	high
93195	MediaWiki 1.23.x < 1.23.15 / 1.26.x < 1.26.4 / 1.27.x < 1.27.1 Multiple Vulnerabilities	Nessus	CGI abuses	high

Detections

Analytics

CVE-2016-6331

high

Tenable Plugins

critical

high

high

high

high