CVE-2025-62508

Citizen is a MediaWiki skin that makes extensions part of the cohesive experience. Citizen from 3.3.0 to 3.9.0 are vulnerable to stored cross-site scripting in the sticky header button message handling. In stickyHeader.js the copyButtonAttributes function assigns innerHTML from a source element’s textContent when copying button labels. This causes escaped HTML in system message content (such as citizen-share, citizen-view-history, citizen-view-edit, and nstab-talk) to be interpreted as HTML in the sticky header, allowing injection of arbitrary script by a user with the ability to edit interface messages. The vulnerability allows a user with the editinterface right but without the editsitejs right (by default the sysop group has editinterface but may not have editsitejs) to execute arbitrary JavaScript in other users’ sessions, enabling unauthorized access to sensitive data or actions. The issue is fixed in 3.9.0.

Citizen is a MediaWiki skin that makes extensions part of the cohesive experience. Citizen from 3.3.0 to 3.9.0 are vulnerable to stored cross-site scripting in the sticky header button message handling. In stickyHeader.js the copyButtonAttributes function assigns innerHTML from a source element’s textContent when copying button labels. This causes escaped HTML in system message content (such as citizen-share, citizen-view-history, citizen-view-edit, and nstab-talk) to be interpreted as HTML in the sticky header, allowing injection of arbitrary script by a user with the ability to edit interface messages. The vulnerability allows a user with the editinterface right but without the editsitejs right (by default the sysop group has editinterface but may not have editsitejs) to execute arbitrary JavaScript in other users’ sessions, enabling unauthorized access to sensitive data or actions. The issue is fixed in 3.9.0.

Summary

The JS implementation for copying button labels to the sticky header in the Citizen skin unescapes HTML characters, allowing for stored XSS through system messages.

Details

In the copyButtonAttributes function in stickyHeader.js, when copying the button labels, the innerHTML of the new element is set to the textContent of the old element: https://github.com/StarCitizenTools/mediawiki-skins-Citizen/blob/f4cbcecf5aca0ae69966b23d4983f9cb5033f319/resources/skins.citizen.scripts/stickyHeader.js#L29-L41 This unescapes any escaped HTML characters and causes the contents of the system messages to be interpreted as HTML.

PoC

1. Edit any of the affected messages (citizen-share, citizen-view-history, citizen-view-edit, nstab-talk) to the following payload: <img src="" onerror="alert('Sticky Header Button XSS')">.
2. Visit any mainpage article in the wiki using the Citizen skin.

<img width="495" height="228" alt="image" src="https://github.com/user-attachments/assets/ac75b8e1-b181-4335-9526-17d6b6f8518e" /> <img width="569" height="157" alt="image" src="https://github.com/user-attachments/assets/c052edb9-ff68-4869-9c66-3ec85e7ff68a" />

Impact

This impacts wikis where a group has the editinterface but not the editsitejs user right. By default, this is the case for the sysop group.

Citizen is a MediaWiki skin that makes extensions part of the cohesive experience. Citizen from 3.3.0 to 3.9.0 are vulnerable to stored cross-site scripting in the sticky header button message handling. In stickyHeader.js the copyButtonAttributes function assigns innerHTML from a source element’s textContent when copying button labels. This causes escaped HTML in system message content (such as citizen-share, citizen-view-history, citizen-view-edit, and nstab-talk) to be interpreted as HTML in the sticky header, allowing injection of arbitrary script by a user with the ability to edit interface messages. The vulnerability allows a user with the editinterface right but without the editsitejs right (by default the sysop group has editinterface but may not have editsitejs) to execute arbitrary JavaScript in other users’ sessions, enabling unauthorized access to sensitive data or actions. The issue is fixed in 3.9.0.

Citizen is a MediaWiki skin that makes extensions part of the cohesive experience. Citizen from 3.3.0 to 3.9.0 are vulnerable to stored cross-site scripting in the sticky header button message handling. In stickyHeader.js the copyButtonAttributes function assigns innerHTML from a source element’s textContent when copying button labels. This causes escaped HTML in system message content (such as citizen-share, citizen-view-history, citizen-view-edit, and nstab-talk) to be interpreted as HTML in the sticky header, allowing injection of arbitrary script by a user with the ability to edit interface messages. The vulnerability allows a user with the editinterface right but without the editsitejs right (by default the sysop group has editinterface but may not have editsitejs) to execute arbitrary JavaScript in other users’ sessions, enabling unauthorized access to sensitive data or actions. The issue is fixed in 3.9.0.

Summary

The JS implementation for copying button labels to the sticky header in the Citizen skin unescapes HTML characters, allowing for stored XSS through system messages.

Details

In the copyButtonAttributes function in stickyHeader.js, when copying the button labels, the innerHTML of the new element is set to the textContent of the old element: https://github.com/StarCitizenTools/mediawiki-skins-Citizen/blob/f4cbcecf5aca0ae69966b23d4983f9cb5033f319/resources/skins.citizen.scripts/stickyHeader.js#L29-L41 This unescapes any escaped HTML characters and causes the contents of the system messages to be interpreted as HTML.

PoC

1. Edit any of the affected messages (citizen-share, citizen-view-history, citizen-view-edit, nstab-talk) to the following payload: <img src="" onerror="alert('Sticky Header Button XSS')">.
2. Visit any mainpage article in the wiki using the Citizen skin.

<img width="495" height="228" alt="image" src="https://github.com/user-attachments/assets/ac75b8e1-b181-4335-9526-17d6b6f8518e" /> <img width="569" height="157" alt="image" src="https://github.com/user-attachments/assets/c052edb9-ff68-4869-9c66-3ec85e7ff68a" />

Impact

This impacts wikis where a group has the editinterface but not the editsitejs user right. By default, this is the case for the sysop group.