Discourse: Block post iframes whose encoded userinfo bypasses the allowed_iframes allowlist
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
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| discourse | discourse | affected |
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No data.
No data.
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| Discourse | Discourse |
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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% (0.216% probability within 30 days)
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ssvc
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| First Time appeared |
Discourse
Discourse discourse |
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| Vendors & Products |
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, the Discourse post sanitizer allowed a stored cross-origin iframe to bypass the allowed_iframes prefix policy when the iframe src contained encoded userinfo. The sanitizer validated a decoded form differently from the stored iframe src, allowing the browser to interpret an attacker-controlled host while the allowlist check accepted the encoded URL as an allowed prefix. An authenticated user with posting privileges could persist the iframe in a post and cause attacker-controlled cross-origin content to be rendered. This issue is fixed in versions 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0. | |
| Title | Discourse: Block post iframes whose encoded userinfo bypasses the allowed_iframes allowlist | |
| Weaknesses | CWE-20 | |
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| Metrics |
cvssV3_1
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