CVE-2026-72728

Discourse: Onebox iframe origin allowlist enforces URL authority boundary

State: Published
Severity: 6.3 Medium
Published: Aug 10, 2026
Updated: Aug 10, 2026
Reserved: Aug 10, 2026

Description

Discourse is an open-source discussion platform. Prior to 2026.1.7, an authenticated user could submit specially formed URLs that bypassed the Onebox allowlist and embedded malicious content in a site. This issue is fixed in versions 2026.1.7, 2026.6.2, 2026.7.1, and 2026.8.0-latest.1.

Scores

CVSS	Score	Vector	Source
3.1	6.3 Medium	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L	GitHub_M

Weaknesses

CWE-20 Improper Input Validation

Affected Products

Product	Versions
discoursediscourse	< 2026.1.7Affected >= 2026.6.0-latest, < 2026.6.2Affected >= 2026.7.0-latest, < 2026.7.1Affected >= 2026.8.0-latest, < 2026.8.0-latest.1Affected

References

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