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CVE-2026-91122

8.7 · HIGH

Discourse is an open-source discussion platform.

Published Sep 24, 2026CWE-79EPSS 0.26%

Overview

CVE-2026-91122 is a high-severity vulnerability. It was published on September 24, 2026 and has a CVSS 3.1 base score of 8.7 (HIGH).

This vulnerability has a CVSS 3.1 base score of 8.7, rated HIGH. It can be exploited remotely over the network. Some level of privileges is 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 video placeholder component allowed crafted HTML to cause an attribute breakout and inject an attacker-controlled event handler. An authenticated user with default trust-level posting privileges could store the crafted placeholder in a post. When another user opened the post and clicked the video play overlay, the handler could execute arbitrary JavaScript in the viewer's session. Default Content Security Policy settings block inline event handlers, but instances with CSP disabled or relaxed could allow the script to read page content and make authenticated requests as the viewer. 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/05d92b8749f68d2626cbe65ec7adde7562a0283dGitHubgithub.com/discourse/discourse/commit/5674b3e6594825c28d2678e55057fd6802f11031GitHubgithub.com/discourse/discourse/commit/c3993e318e172389be5c98455177876f1dd87ddaGitHubgithub.com/discourse/discourse/commit/d7126af3264b672d2201d84c18a37cb8627424a8GitHubgithub.com/discourse/discourse/pull/42882GitHubgithub.com/discourse/discourse/security/advisories/GHSA-8m44-f6g9-7cg7

How CyberStrike helps

Frequently asked questions

What is CVE-2026-91122?

CVE-2026-91122 is a high-severity vulnerability. It was published on September 24, 2026 and has a CVSS 3.1 base score of 8.7 (HIGH).

How severe is CVE-2026-91122?

This vulnerability has a CVSS 3.1 base score of 8.7, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2026-91122?

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-2026-91122?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-91122 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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