CVE-2026-27570

MEDIUM

Discourse Vulnerable to Stored XSS via Shared AI Conversation Onebox

Title source: cna

Description

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.

References (4)

[X_Refsource_Confirm] https://github.com/discourse/discourse/security/advisories/GHSA-hfxw-89hw-vwmv

[X_Refsource_Misc] https://github.com/discourse/discourse/commit/43a5a60b595f0120e6adfc131f2408508fe341f1

View Writeup ZIP pw:eip

[X_Refsource_Misc] https://github.com/discourse/discourse/commit/c14f8f52b7999328bd9f8665f2ecfa24dadc4bf1

[X_Refsource_Misc] https://github.com/discourse/discourse/commit/f2aafa5c7467c94fcd4ebd36785a98e77ca088cc

Scores

CVSS v3 6.1

EPSS 0.0001

EPSS Percentile 1.8%

Attack Vector NETWORK

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CISA SSVC

Vulnrichment

Exploitation none

Automatable no

Technical Impact partial

Details

CWE

CWE-79

Status published

Products (5)

discourse/discourse 2026.3.0

discourse/discourse 2026.1.0 - 2026.1.2

discourse/discourse >= 2026.1.0-latest, < 2026.1.2

discourse/discourse >= 2026.2.0-latest, < 2026.2.1

discourse/discourse = 2026.3.0-latest

Published Mar 19, 2026

Tracked Since Mar 20, 2026