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CVE-2026-91123

7.2 · HIGH

Discourse is an open-source discussion platform.

Published Sep 24, 2026CWE-22EPSS 0.29%

Overview

CVE-2026-91123 is a high-severity vulnerability. It was published on September 24, 2026 and has a CVSS 3.1 base score of 7.2 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.2, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/discourse/discourse/commit/042d7b159beda4f74d23e245e8b2e396d9ff8318GitHubgithub.com/discourse/discourse/commit/097ce5600a2d74d9c68e57974597ab2684bd2a24GitHubgithub.com/discourse/discourse/commit/0b5a27e689925edce9ba9b14110022435d2b94beGitHubgithub.com/discourse/discourse/commit/142f5155ad8e56ddb8012c4e70c69a03dedc0579GitHubgithub.com/discourse/discourse/pull/42882GitHubgithub.com/discourse/discourse/security/advisories/GHSA-6pwj-wgg8-4rjc

How CyberStrike helps

Frequently asked questions

What is CVE-2026-91123?

CVE-2026-91123 is a high-severity vulnerability. It was published on September 24, 2026 and has a CVSS 3.1 base score of 7.2 (HIGH).

How severe is CVE-2026-91123?

This vulnerability has a CVSS 3.1 base score of 7.2, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-91123?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-91123?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-91123 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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