Discourse Onebox Allowlist Bypass (<2026.1.7)
CVE-2026-72728 Published on August 10, 2026
Discourse: Onebox iframe origin allowlist enforces URL authority boundary
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.
Vulnerability Analysis
CVE-2026-72728 is exploitable with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to be low. considered to have a small impact on confidentiality and integrity and availability.
Weakness Type
Improper Input Validation
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
Products Associated with CVE-2026-72728
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Affected Versions
discourse:- Version < 2026.1.7 is affected.
- Version >= 2026.6.0-latest, < 2026.6.2 is affected.
- Version >= 2026.7.0-latest, < 2026.7.1 is affected.
- Version >= 2026.8.0-latest, < 2026.8.0-latest.1 is affected.