Discourse: Stored oEmbed HTML injection via allowed iframe
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% (0.417% probability within 30 days)
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Discourse
Discourse discourse |
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Discourse
Discourse discourse |
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ssvc
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| Description | Discourse is an open-source discussion platform. Prior to 2026.9.0, 2026.8.1, 2026.7.3, and 2026.1.9, oEmbed processing treated an entire attacker-controlled HTML fragment as trusted when the fragment contained an iframe whose source matched the configured allowlist. A user with posting permission who controlled a public webpage and its oEmbed response could combine an allowlisted iframe with unrelated sibling HTML or CSS, causing stored visual overlays or other styled content to appear in post content and enabling misleading or fraudulent user interfaces. Exploitation requires a posting account, control of the fetched webpage and oEmbed response, and an allowlisted iframe source. The issue affects content integrity but does not expose restricted data, disrupt availability, or require interaction with Discourse Content Security Policy. This issue is fixed in versions 2026.9.0, 2026.8.1, 2026.7.3, and 2026.1.9. | |
| Title | Discourse: Stored oEmbed HTML injection via allowed iframe | |
| Weaknesses | CWE-79 | |
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| Metrics |
cvssV3_1
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