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CVE-2026-91120— Discourse: Stored HTML injection in video notification emails

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 是一个开源的讨论平台。在版本 2026.1.8、2026.6.3、2026.7.2 和 2026.8.0 之前，当 Discourse 生成通知邮件或聊天摘要时，惰性视频嵌入（lazy video embeds）中由提供者控制的视频标题可能被重新解析为 HTML。拥有普通发帖权限的用户可以在启用了 YouTube、Vimeo 或 TikTok 视频提供者的帖子中，创建一个标题包含 HTML 标记的视频嵌入；在邮件和聊天摘要的渲染过程中，这些标记会被直接插入到输出内容中，而不是仅作为纯文本处理。使

CVSS 5.4 · Medium EPSS 0.20% · P9
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I. Basic Information for CVE-2026-91120

Vulnerability Information
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Vulnerability Title
Discourse: Stored HTML injection in video notification emails
Source: CVE Program / CVE List V5
Vulnerability Description
Discourse is an open-source discussion platform. Prior to 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0, provider-controlled video titles in lazy video embeds could be reparsed as HTML when Discourse generated notification emails or chat summaries. A user with standard posting privileges could create a post for an enabled YouTube, Vimeo, or TikTok provider whose title contained markup, and the email and chat-summary rendering path would place that markup into the output instead of treating it solely as text. Recipients using HTML-capable email clients could see injected content, potentially including event handlers, but the issue did not directly expose a Discourse browser session or affect the forum page itself. Lazy video embeds must be enabled, which is the default configuration. This issue is fixed in versions 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A: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

Affected Products

Vendor Product Affected Versions CPE Subscribe
discourse discourse < 2026.8.0 -

II. Public POCs for CVE-2026-91120

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III. Intelligence Information for CVE-2026-91120

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Other References for CVE-2026-91120 (6)

Same Patch Batch · discourse · 2026-09-24 · 9 CVEs total

CVE-2026-91122 8.7 HIGH Discourse: Chat MessageBus delivers read-restricted messages to unauthorized users
CVE-2026-91123 7.2 HIGH Discourse: Reject literal backslash path separators in iframe src traversal guard
CVE-2026-91133 6.5 MEDIUM Discourse: Escape LIKE metacharacters in upload paths to prevent disclosure
CVE-2026-91119 6.4 MEDIUM Discourse: Encode action_code_who in mention URLs
CVE-2026-91134 5.4 MEDIUM Discourse: Block post iframes whose encoded userinfo bypasses the allowed_iframes allowlis
CVE-2026-91121 5.0 MEDIUM Discourse: Chat upload filenames rendered as raw HTML in excerpts
CVE-2026-91132 4.3 MEDIUM Discourse: Wildcard iframe origin allowlist bypass via authority separators
CVE-2026-84302 4.2 MEDIUM Discourse: Non-participant moderators can read, edit, and delete PM content through Discou

IV. Related Vulnerabilities

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

V. Comments for CVE-2026-91120

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