Discourse up to 2026.1.7/2026.6.2/2026.7.1/2026.7.x Video Placeholder cross site scripting

Summaryinfo

A vulnerability, which was classified as problematic, was found in Discourse up to 2026.1.7/2026.6.2/2026.7.1/2026.7.x. This affects an unknown part of the component Video Placeholder. Executing a manipulation can lead to cross site scripting. This vulnerability is tracked as CVE-2026-91122. The attack can be launched remotely. No exploit exists. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Discourse up to 2026.1.7/2026.6.2/2026.7.1/2026.7.x. It has been declared as problematic. This vulnerability affects some unknown functionality of the component Video Placeholder. The manipulation with an unknown input leads to a cross site scripting vulnerability. The CWE definition for the vulnerability is CWE-79. 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. As an impact it is known to affect integrity. CVE summarizes:

Discourse is an open-source discussion platform. Prior to 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0, the video placeholder component allowed crafted HTML to cause an attribute breakout and inject an attacker-controlled event handler. An authenticated user with default trust-level posting privileges could store the crafted placeholder in a post. When another user opened the post and clicked the video play overlay, the handler could execute arbitrary JavaScript in the viewer's session. Default Content Security Policy settings block inline event handlers, but instances with CSP disabled or relaxed could allow the script to read page content and make authenticated requests as the viewer. This issue is fixed in versions 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0.

The advisory is available at github.com. This vulnerability was named CVE-2026-91122 since 09/14/2026. The exploitation appears to be easy. The attack can be initiated remotely. Successful exploitation requires user interaction by the victim. The technical details are unknown and an exploit is not available. This vulnerability is assigned to T1059.007 by the MITRE ATT&CK project.

Upgrading to version 2026.1.8, 2026.6.3, 2026.7.2 or 2026.8.0 eliminates this vulnerability.

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Type

• Chat Software

Name

• Discourse

Version

• 2026.0
• 2026.1
• 2026.1.0
• 2026.1.1
• 2026.1.2
• 2026.1.3
• 2026.1.4
• 2026.1.5
• 2026.1.6
• 2026.1.7
• 2026.2
• 2026.3
• 2026.4
• 2026.5
• 2026.6
• 2026.6.0
• 2026.6.1
• 2026.6.2
• 2026.7
• 2026.7.0
• 2026.7.1

License

• open-source

Website

• Product: https://github.com/discourse/discourse/

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