CVE-2026-91156High· 7.5▾ TwilightDiscourse 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 …
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 41.3 · likelihood 0.1 · exploitation 0
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Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake.
Exploit-prediction probability, daily snapshots since Oct 16.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via NVD
0.5%
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.
Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
Connected by shared product, vendor, weakness, or advisory.
CVE-2026-84302Medium· 4.2Discourse is an open-source discussion platform
CVE-2017-20290Medium· 6.1Discourse < 1.9.0.beta13 Reflected XSS via /email/unsubscribed
CVE-2026-91159High· 7.7Discourse is an open-source discussion platform
CVE-2026-91157High· 7.5Discourse is an open-source discussion platform
CVE-2026-91119Medium· 6.4Discourse is an open-source discussion platform
CVE-2026-91120Medium· 5.4Discourse is an open-source discussion platform