Discourse: Wildcard iframe origin allowlist bypass via authority separators
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
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No CVSS v4.0
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.136% probability within 30 days)
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ssvc
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Discourse
Discourse discourse |
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Discourse
Discourse discourse |
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| 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. | |
| Title | Discourse: Wildcard iframe origin allowlist bypass via authority separators | |
| Weaknesses | CWE-346 | |
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| Metrics |
cvssV3_1
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