VULNERABILITY INTELLIGENCE
CVE-2026-91123
CVSS score7.2 HIGH
EPSS probability0.29%
CISA KEVNot currently listed
Published2026-09-24
Last modified2026-09-24
CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
Description
Discourse is an open-source discussion platform. Prior to 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0, the iframe src traversal guard did not treat literal backslashes as path separators after decoded dot segments. A crafted source could therefore pass an allowed_iframes subpath check while browser URL normalization moved the iframe outside the intended allowed path. The resulting iframe could load content from a location that the administrator did not allow. This issue is fixed in versions 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0.
Weakness classification
- security-advisories@github.com: CWE-22