CVE-2026-27740

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.

CVSS v3 6.1 MEDIUM

6.1^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.8 / Impact : 2.7

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact LOW

Integrity Impact LOW

Availability Impact NONE

Scope CHANGED

References

Link	Resource
https://github.com/discourse/discourse/commit/44b84439df7e4424b2e7f216fd8fdd7dacff2227	Patch
https://github.com/discourse/discourse/commit/8ae7cb2414d6918d7fc45e1fda7ffbb32912a975	Patch
https://github.com/discourse/discourse/commit/ed70949f2c047196f33cfa94f2819df29c5d1e5f	Patch
https://github.com/discourse/discourse/security/advisories/GHSA-95hc-42c6-wvvr	Vendor Advisory

Configurations

Configuration 1 (hide)

OR	cpe:2.3:a:discourse:discourse::::::::
	cpe:2.3:a:discourse:discourse::::::::
	cpe:2.3:a:discourse:discourse:2026.3.0::::latest:::

History

No history.

Information

Published : 2026-03-19 21:17

Updated : 2026-03-25 00:58

NVD link : CVE-2026-27740

Mitre link : CVE-2026-27740

CVE.ORG link : CVE-2026-27740

JSON object : View

Products Affected

discourse

discourse

CWE

CWE-79

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

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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."}, {"lang": "es", "value": "Discourse es una plataforma de discusi\u00f3n de c\u00f3digo abierto. Las versiones anteriores a 2026.3.0-latest.1, 2026.2.1 y 2026.1.2 tienen una vulnerabilidad de cross-site scripting que surge porque el sistema conf\u00eda en la salida sin procesar de un Modelo de Lenguaje Grande de IA (LLM) y la renderiza usando htmlSafe en la interfaz de la Cola de Revisi\u00f3n sin una sanitizaci\u00f3n adecuada. Un atacante malicioso puede usar t\u00e9cnicas v\u00e1lidas de Inyecci\u00f3n de Prompt para forzar a la IA a devolver una carga \u00fatil maliciosa (p. ej., etiquetas). Cuando un miembro del personal (Administrador/Moderador) ve la publicaci\u00f3n marcada en la Cola de Revisi\u00f3n, la carga \u00fatil se ejecuta. Las versiones 2026.3.0-latest.1, 2026.2.1 y 2026.1.2 contienen un parche. Como soluci\u00f3n alternativa, deshabilite temporalmente los scripts de automatizaci\u00f3n de triaje de IA."}], "lastModified": "2026-03-25T00:58:33.730", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:discourse:discourse:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "4BE96625-3609-410C-B41E-4A824C1A57C0", "versionEndExcluding": "2026.1.2", "versionStartIncluding": "2026.1.0"}, {"criteria": "cpe:2.3:a:discourse:discourse:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "FD31CF04-CF2F-4FB9-8880-9243BC7671A7", "versionEndExcluding": "2026.2.1", "versionStartIncluding": "2026.2.0"}, {"criteria": "cpe:2.3:a:discourse:discourse:2026.3.0:*:*:*:latest:*:*:*", "vulnerable": true, "matchCriteriaId": "E3FE9277-4F6B-4FD0-991F-F0FB8D226E1C"}], "operator": "OR"}]}], "sourceIdentifier": "security-advisories@github.com"}