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

Quick assessment

Affected
discourse discourse
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Discourse是Discourse开源的一套开源的社区讨论平台。该平台包括社区、电子邮件和聊天室等功能。 Discourse 2026.3.0-latest.1之前版本、2026.2.1之前版本和2026.1.2之前版本存在跨站脚本漏洞，该漏洞源于系统信任AI大语言模型的原始输出并在Review Queue界面中使用htmlSafe渲染而未进行充分清理，可能导致跨站脚本攻击。

AI Predicted 8.2 Difficulty: Moderate EPSS 0.32% · P25
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I. Basic Information for CVE-2026-27740

Vulnerability Information
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Vulnerability Title
Discourse has Stored XSS in AI Triage Automation
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
在Web页面生成时对输入的转义处理不恰当(跨站脚本)
Source: CVE Program / CVE List V5
Vulnerability Title
Discourse 跨站脚本漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Discourse是Discourse开源的一套开源的社区讨论平台。该平台包括社区、电子邮件和聊天室等功能。 Discourse 2026.3.0-latest.1之前版本、2026.2.1之前版本和2026.1.2之前版本存在跨站脚本漏洞，该漏洞源于系统信任AI大语言模型的原始输出并在Review Queue界面中使用htmlSafe渲染而未进行充分清理，可能导致跨站脚本攻击。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
discourse discourse >= 2026.1.0-latest, < 2026.1.2 -

II. Public POCs for CVE-2026-27740

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III. Intelligence Information for CVE-2026-27740

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Patches & Fixes for CVE-2026-27740 (3)

Vendor Advisories for CVE-2026-27740 (1)

Same Patch Batch · discourse · 2026-03-19 · 17 CVEs total

CVE-2026-33355 6.5 MEDIUM Discourse filters whisper posts from private-posts feed
CVE-2026-33410 5.4 MEDIUM Discourse hardens chat DM channel creation and expansion
CVE-2026-27454 5.3 MEDIUM Discourse has check revision visibility on posts endpoint
CVE-2026-33395 4.4 MEDIUM Discourse has stored click‑based XSS via Graphviz SVG javascript: links
CVE-2026-32099 4.3 MEDIUM Discourse prevents hidden profile data leak via user onebox
CVE-2026-33393 4.3 MEDIUM Discourse fixes loose hostname matching in spam host allowlist
CVE-2026-27166 4.1 MEDIUM Discourse vulnerable to HTML injection via prohibited iframe URLs
CVE-2026-33394 2.7 LOW Discourse leaks PM post edits to moderators
CVE-2026-33408 2.2 LOW Discourse has Improper Authorization in "Post Edits" Report For Moderators
CVE-2026-27491 Discourse has a bypass of official warnings messages by non-staff users
CVE-2026-27570 Discourse Vulnerable to Stored XSS via Shared AI Conversation Onebox
CVE-2026-27934 Discourse leaks private topic title and post excerpt via user action API endpoint
CVE-2026-27935 Discourse leaks private topic metadata to non-authorized users
CVE-2026-27936 Discourse discloses restricted post-action counts to non-privileged users
CVE-2026-28282 Discourse vulnerable to group membership addition permission bypass via discourse-policy p
CVE-2026-29072 Discourse missing permission check for policy creation in discourse-policy

IV. Related Vulnerabilities

Same product: discourse
Same vendor: discourse
Same weakness: CWE-79

V. Comments for CVE-2026-27740

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