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Stored XSS in user registration date message

Moderate
alistair3149 published GHSA-2v3v-3whp-953h Jun 11, 2025

Package

Citizen (MediaWiki)

Affected versions

>= 64cb5d7ab3a6dc0381fae54b31e8fc4afadc8beb

Patched versions

93c36ac778397e0e7c46cf7adb1e5d848265f1bd

Description

Summary

Various date messages returned by Language::userDate are inserted into raw HTML, allowing anybody who can edit those messages to insert arbitrary HTML into the DOM.

Details

The result of $this->lang->userDate( $timestamp, $this->user ) returns unescaped values, but is inserted as raw HTML by Citizen:

mediawiki-skins-Citizen/includes/Components/CitizenComponentUserInfo.php

Lines 55 to 60 in 072e436

$html = sprintf(
'<time class="citizen-user-regdate" datetime="%s">%s</time>',
wfTimestamp( TS_ISO_8601, $timestamp ),
// Since this is not accessible by anon, we can use user language
$this->lang->userDate( $timestamp, $this->user )
);

PoC

  1. Go to any page using citizen with the uselang parameter set to x-xss and while being logged in
    Depending on the registration date of the account you're logged in with, various messages can be shown. In my case, it's november:
    image

Impact

This impacts wikis where a group has the editinterface but not the editsitejs user right.

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
High
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N

CVE ID

CVE-2025-49578

Weaknesses

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. Learn more on MITRE.

Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)

The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special characters such as <, >, and & that could be interpreted as web-scripting elements when they are sent to a downstream component that processes web pages. Learn more on MITRE.

Credits