CVE-2026-91156Discourse: Chat MessageBus delivers read-restricted messages to unauthorized users
Updated under an hour ago ()
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It affects discourse. Add what you run to find out whether that includes you.
EPSS puts the chance of exploitation in the next 30 days at 0.48%, higher than 40% of scored CVEs.
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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.
- CVSS
- 7.5 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- Weakness (CWE)
- CWE-862
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- 0.48% (percentile 40)
- Assigned by
- GitHub_M
- NVD analysis
- Deferred
- Record last updated
- Oct 14, 2026
- First seen by InfoSec Signals
- Oct 14, 2026
Affected products
discourse discourse discourse:discourse (from the name) | before 2026.1.9; from 2026.7.0-latest, < 2026.7.3; from 2026.8.0-latest, < 2026.8.1; from 2026.9.0-latest, < 2026.9.0 | CNA record |
References
- https://github.com/discourse/discourse/security/advisories/GHSA-gh4f-qr62-vx8qx-refsource-confirm
- https://github.com/discourse/discourse/commit/046fb7bfd68a5b95e63dda88c3c73877c5cf9d5ex-refsource-misc
- https://github.com/discourse/discourse/commit/87b31bf60a7827f075634254379a1dcbaba409cbx-refsource-misc
- https://github.com/discourse/discourse/commit/ba74bb404ab4439f5b1f0204e848d62099db8ae1x-refsource-misc
- https://github.com/discourse/discourse/commit/cac1f26f275cec3dc1dd51dfdac2b3d1a4ec50f8x-refsource-misc
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.