CVE-2026-91123

Published: Sep 24, 2026Modified: Sep 24, 2026Deferred

7.2

Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N

Exploitability: 3.9 / Impact: 2.7

Source: security-advisories@github.com (Secondary)

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.

Related CWEs

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

References (6)

https://github.com/discourse/discourse/commit/042d7b159beda4f74d23e245e8b2e396d9ff8318

Source: security-advisories@github.com

https://github.com/discourse/discourse/commit/097ce5600a2d74d9c68e57974597ab2684bd2a24

Source: security-advisories@github.com

https://github.com/discourse/discourse/commit/0b5a27e689925edce9ba9b14110022435d2b94be

Source: security-advisories@github.com

https://github.com/discourse/discourse/commit/142f5155ad8e56ddb8012c4e70c69a03dedc0579

Source: security-advisories@github.com

https://github.com/discourse/discourse/pull/42882

Source: security-advisories@github.com

https://github.com/discourse/discourse/security/advisories/GHSA-6pwj-wgg8-4rjc

Source: security-advisories@github.com

Timeline

No history available yet.