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CVE-2026-91156 Details

ANALYZED

This CVE record has been analyzed and enriched by NVDAPI.com as an independent party.

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.

Metrics

CVSS 3.x Severity and Vector Strings:

VolerionCVSS-B:4.3 MEDIUMVector:CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

CNA: [email protected]CVSS-B:7.5 HIGHVector:CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

References to Advisories, Solutions, and Tools

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URL	Source(s)	Tag(s)
https://github.com/discourse/discourse/commit/046fb7bfd68a5b95e63dda88c3c73877c5cf9d5e	[email protected]	Source CodeVendor
https://github.com/discourse/discourse/commit/87b31bf60a7827f075634254379a1dcbaba409cb	[email protected]	Source CodeVendor
https://github.com/discourse/discourse/commit/ba74bb404ab4439f5b1f0204e848d62099db8ae1	[email protected]	Source CodeVendor
https://github.com/discourse/discourse/commit/cac1f26f275cec3dc1dd51dfdac2b3d1a4ec50f8	[email protected]	Source CodeVendor
https://github.com/discourse/discourse/security/advisories/GHSA-gh4f-qr62-vx8q	[email protected]	AdvisoryRemedyVendor

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-862	Missing Authorization	[email protected]

Affected Products

Product	Versions
Discourse	>= 2026.8.0-latest (semver) >= 2026.7.0-latest (semver) >= 2026.1.0-latest (semver)
CPE cpe:2.3:a:discourse:discourse:::::::: Remediation Upgrade: 2026.9.0moderate effort Upgrade: 2026.8.1moderate effort Upgrade: 2026.7.3moderate effort Upgrade: 2026.1.9moderate effort Workaround:low effort Remove the disallowed user from the category, or avoid using the affected read-restricted category with the user disallowed from chat.

Change History

2 change records found show changes

Date	Action	Recorded By
Oct 14, 2026	CVE Modified	CISA-ADP
Oct 14, 2026	New CVE Received	[email protected]