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CVE-2026-91119— Discourse: Encode action_code_who in mention URLs

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，topic small-action（话题小操作）和 nested-activity-log（嵌套活动日志）组件会将自由格式的 action_code_who 值直接插值到 mention-link（提及链接）的 href 属性中，而未进行 URL 编码。一个包含引号的用户显示名称可以终止预期的 URL 属性，并将攻击者控制的元素注入到受信任的已渲染标记中。虽然可见的提及文本已被转义，

CVSS 6.4 · Medium EPSS 0.20% · P9
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I. Basic Information for CVE-2026-91119

Vulnerability Information
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Vulnerability Title
Discourse: Encode action_code_who in mention URLs
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, the topic small-action and nested-activity-log components interpolated the free-form action_code_who value into mention-link href attributes without URL encoding. A quote-bearing display name could terminate the intended URL attribute and inject attacker-controlled elements into the trusted rendered markup. Although the visible mention text was escaped, the unencoded path component allowed stored HTML injection when another user viewed the affected topic action or activity log. 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:C/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-2026-91119

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III. Intelligence Information for CVE-2026-91119

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Other References for CVE-2026-91119 (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-2026-91134 5.4 MEDIUM Discourse: Block post iframes whose encoded userinfo bypasses the allowed_iframes allowlis
CVE-2026-91120 5.4 MEDIUM Discourse: Stored HTML injection in video notification emails
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-2026-91119

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