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LLMMedium

CVE-2026-27740: Discourse is an open-source discussion platform. Versions prior to 2026.3.0-latest.1, 2026.2.1, and …

Occurred
Mar 19, 2026
Published
Mar 19, 2026
Source
NVD CVE

Summary

Discourse is an open-source discussion platform. Versions prior to 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 have a cross-site scripting vulnerability that arises because the system trusts the raw output from an AI Large Language Model (LLM) and renders it using htmlSafe in the Review Queue interface without adequate sanitization. A malicious attacker can use valid Prompt Injection techniques to force the AI to return a malicious payload (e.g., tags). When a Staff member (Admin/Moderator) views the flagged post in the Review Queue, the payload executes. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. As a workaround, temporarily disable AI triage automation scripts.

Tags

  • CVE
  • CVE-2026-27740
  • cvss:MEDIUM

Classification

Category confidence: 90%
Severity confidence: 85%

Rationale: Vulnerability involves LLM prompt injection leading to XSS, but limited to admin view and patched.

Classifier: Qwen/Qwen3.5-35B-A3B-FP8

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