CVE-2026-91122 (GCVE-0-2026-91122)

Vulnerability from cvelistv5 – Published: 2026-09-24 16:56 – Updated: 2026-09-24 17:25
VLAI
Title
Discourse: Chat MessageBus delivers read-restricted messages to unauthorized users
Summary
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.
Severity
8.7 (High)
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
SSVC
Exploitation: none Automatable: no Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-24 17:25 UTC
CWE
  • CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Assigner
GitHub_M CNA under the mitre root
CNA scorecard C 72/100 over 7843 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
discourse discourse Affected: < 2026.8.0
Affected: >= 2026.7.0-latest, < 2026.7.2
Affected: >= 2026.6.0-latest, < 2026.6.3
Affected: >= 2026.1.0-latest, < 2026.1.8
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

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