Medium severity · published Aug 10, 2026
CVE-2026-72728
Discourse: Onebox iframe origin allowlist enforces URL authority boundary
6.3
CVSS
0.3%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
Low
Integrity
Low
Availability
Low
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 24% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
DI
discourse · discourse
< 2026.1.7; >= 2026.6.0-latest, < 2026.6.2; >= 2026.7.0-latest, < 2026.7.1; >= 2026.8.0-latest, < 2026.8.0-latest.1 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-72728
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-72728
github.com
https://github.com/discourse/discourse/commit/92eec47e8b477cb8b4ccdb237e26dc1ba8f8b76b
github.com
https://github.com/discourse/discourse/security/advisories/GHSA-qp9j-3v7r-wrvr
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