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CVE-2026-91132— Discourse: Wildcard iframe origin allowlist bypass via authority separators

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 是一个开源讨论平台。在版本 2026.1.8、2026.6.3、2026.7.2 和 2026.8.0 之前，如果站点在 allowed_iframes 设置中使用了通配符模式，则可能接受一个构造的 iframe URL，其允许列表中的后缀出现在 URL 授权分隔符之后。通配符来源检查匹配的是允许的域名文本，而浏览器 URL 解析则选择了不同的、由攻击者控制的来源。具有发帖权限的用户可以通过帖子或 Onebox oEmbed 响应利用此漏洞，导致由攻击者控制的 iframe 在独立于允许列表域名

CVSS 4.3 · Medium EPSS 0.14% · P2
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I. Basic Information for CVE-2026-91132

Vulnerability Information
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Vulnerability Title
Discourse: Wildcard iframe origin allowlist bypass via authority separators
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, sites using wildcard patterns in the allowed_iframes setting could accept a crafted iframe URL whose allowlisted suffix appeared after a URL authority separator. The wildcard origin check matched the allowed domain text, while browser URL parsing selected a different attacker-controlled origin. A user with posting privileges could exploit the flaw through a post or a Onebox oEmbed response and cause an attacker-controlled iframe to be rendered independently of the allowlisted domain. Successful exploitation requires a site-configured wildcard iframe pattern and the ability to create a post or trigger an oEmbed request for an attacker-controlled URL. 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:N/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
源验证错误
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
discourse discourse < 2026.8.0 -

II. Public POCs for CVE-2026-91132

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III. Intelligence Information for CVE-2026-91132

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Other References for CVE-2026-91132 (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-2026-91120 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-2026-84302 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-346

V. Comments for CVE-2026-91132

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