Exposure of Sensitive Information to an Unauthorized Actor vulnerability in Wikimedia Foundation CheckUser. This issue affects CheckUser: from 1.45.0 before 1.45.2.

According to its self-reported version number, the instance of MediaWiki hosted on the remote web server is prior to 1.43.7, 1.44.x prior to 1.44.4 or 1.45.x prior to 1.45.2. It is, therefore, affected by a number of vulnerabilities as follows.

- Block UI elements in the 'tools' sidebar reveal the presence of an autoblocked IP. (CVE-2026-34092)

- RecentChanges entries expose suppressed content via generated log page HTML. (CVE-2026-34088)

- User localization is leaked by AbuseFilter + EventStream. (CVE-2026-34091)

- Suggested investigations do not handle suppressed usernames. (CVE-2026-34090)

- The Users API leaks whether privileged users have their user groups disabled for lack of 2FA. (CVE-2026-34087)

- Special:UserRights allows viewing user rights from a private wiki. (CVE-2026-34093)

- AbuseFilter misuses ::userCanBitfield, exposing access-controlled information. (CVE-2026-34086)

- The customized help link for the page protection indicator is relative to the subpage name. (CVE-2026-34094)

- A memory leak in Scribunto causes runJobs.php to run out of memory. (CVE-2026-34089)

- action=raw with a Special:Mypage subpage responds with text/html on a javascript request. (CVE-2026-34095)

- The Notifications (Echo) API can be used by any OAuth tool. (CVE-2026-5266)

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

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - Exposure of Sensitive Information to an Unauthorized Actor vulnerability in Wikimedia Foundation     CheckUser. This issue affects CheckUser: from 1.45.0 before 1.45.2. (CVE-2026-34090)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Severity
115327	MediaWiki 1.45.x < 1.45.2 Multiple Vulnerabilities	Web App Scanning	Component Vulnerability	medium
115326	MediaWiki 1.44.x < 1.44.4 Multiple Vulnerabilities	Web App Scanning	Component Vulnerability	medium
115325	MediaWiki < 1.43.7 Multiple Vulnerabilities	Web App Scanning	Component Vulnerability	medium
305183	Linux Distros Unpatched Vulnerability : CVE-2026-34090	Nessus	Misc.	medium

Detections

Analytics

CVE-2026-34090

medium

Tenable Plugins

medium

medium

medium

medium