Discourse has Stored XSS in AI Triage Automation (CVE-2026-27740)

Summary

Discourse has Stored XSS in AI Triage Automation

Original description

The description as published by the source.

Discourse is an open-source discussion platform. Versions prior to 2026.3.0, 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, 2026.2.1, and 2026.1.2 contain a patch. As a workaround, temporarily disable AI triage automation scripts.

Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV

Affected packages

Bitnami discourse

[{"type":"SEMVER","events":[{"introduced":"2026.1.0"},{"fixed":"2026.1.2"},{"introduced":"2026.2.0"},{"fixed":"2026.2.1"},{"introduced":"2026.3.0"},{"fixed":"2026.3.0"}]}]

References

advisory github.com
patch github.com
patch github.com
patch github.com
web nvd.nist.gov