CVE-2026-91123
Discourse: Reject literal backslash path separators in iframe src traversal guard
- State
- Published
- Severity
- 7.2 High
- Published
- Sep 24, 2026
- Updated
- Sep 24, 2026
- Reserved
- Sep 14, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 7.2 High | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N | GitHub_M |
Weaknesses
- CWE-22 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Affected Products
| Product | Versions |
|---|---|
discoursediscourse |
|
References
- https://github.com/discourse/discourse/security/advisories/GHSA-6pwj-wgg8-4rjc
- https://github.com/discourse/discourse/pull/42882
- https://github.com/discourse/discourse/commit/042d7b159beda4f74d23e245e8b2e396d9ff8318
- https://github.com/discourse/discourse/commit/097ce5600a2d74d9c68e57974597ab2684bd2a24
- https://github.com/discourse/discourse/commit/0b5a27e689925edce9ba9b14110022435d2b94be
- https://github.com/discourse/discourse/commit/142f5155ad8e56ddb8012c4e70c69a03dedc0579
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