CVE-2026-27570 MEDIUM

CVE-2026-27570: Discourse Vulnerable to Stored XSS via Shared AI Conversation Onebox

Vendor Discourse
Product discourse
Weakness CWE-79 · XSS
Published March 19, 2026
Last update March 24, 2026
View on NVD All CVEs

CVSS base score

5.1/10
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction —
Confidentiality —
Integrity —

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

What the vulnerability does

01Description

Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, the onebox method in the SharedAiConversation model renders the conversation title directly into HTML without proper sanitization. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. As a workaround, tighten access by changing the `ai_bot_public_sharing_allowed_groups` site setting.

Key dates

02Disclosure timeline

March 19, 2026 CVE published
March 24, 2026 Record updated