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CVE-2026-91156

7.5 · HIGH

Discourse is an open-source discussion platform.

Published Oct 14, 2026CWE-862EPSS 0.48%

Overview

CVE-2026-91156 is a high-severity vulnerability. It was published on October 14, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.5, 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 2026.9.0, 2026.8.1, 2026.7.3, and 2026.1.9, MessageBus audience calculation could deliver messages from a read-restricted category chat channel to an authenticated user who could view the category but was not allowed to use Chat under the site's group restrictions. The publication path bounded events by category visibility without also enforcing Chat eligibility, exposing live and recent message content available in the MessageBus backlog. The issue does not permit retrieval of the channel's full history through the Chat API and does not permit message creation or modification. This issue is fixed in versions 2026.9.0, 2026.8.1, 2026.7.3, and 2026.1.9.

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/046fb7bfd68a5b95e63dda88c3c73877c5cf9d5eGitHubgithub.com/discourse/discourse/commit/87b31bf60a7827f075634254379a1dcbaba409cbGitHubgithub.com/discourse/discourse/commit/ba74bb404ab4439f5b1f0204e848d62099db8ae1GitHubgithub.com/discourse/discourse/commit/cac1f26f275cec3dc1dd51dfdac2b3d1a4ec50f8GitHubgithub.com/discourse/discourse/security/advisories/GHSA-gh4f-qr62-vx8q

How CyberStrike helps

Frequently asked questions

What is CVE-2026-91156?

CVE-2026-91156 is a high-severity vulnerability. It was published on October 14, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-91156?

This vulnerability has a CVSS 3.1 base score of 7.5, 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-2026-91156?

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-2026-91156?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-91156 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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