CVE-2026-91122 json
Discourse: Chat MessageBus delivers read-restricted messages to unauthorized users
published 2026-09-24 45 d ago modified 2026-10-01 39 d ago also BIT-discourse-2026-91122 , EUVD-2026-86302 , GHSA-8m44-f6g9-7cg7
- cvss
- 8.7
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.3%
- EPSS 0.3% chance of exploitation in 30 days, percentile 17%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- bitnami discourse 2026.8.0
- discourse discourse 2026.1.8, 2026.6.3, 2026.7.2, 2026.8.0
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
- Assessed
- 45 d ago
Exploit prediction
0.26% chance of exploitation in the next 30 days, higher than 17% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 8.7 | CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N |
| OSV | 3.1 | 8.7 | CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| bitnami | discourse | <2026.8.0 |
2026.8.0 |
Affected products
- discourse discourse
Classification
- Weakness
-
- CWE-79 Improper Neutralization of Input During Web Page Generation
References
-
github.com
/discourse/discourse/pull/42882
web
-
github.com
/discourse/discourse/commit/05d92b8749f68d2626cbe65ec7adde7562a0283d
web
-
github.com
/discourse/discourse/commit/5674b3e6594825c28d2678e55057fd6802f11031
web
-
github.com
/discourse/discourse/commit/c3993e318e172389be5c98455177876f1dd87dda
web
-
github.com
/discourse/discourse/commit/d7126af3264b672d2201d84c18a37cb8627424a8
web
-
github.com
/discourse/discourse/security/advisories/GHSA-8m44-f6g9-7cg7
web
-
nvd.nist.gov
/vuln/detail/CVE-2026-91122
web
Sources
- CVE List CVE-2026-91122
- NVD CVE-2026-91122
- OSV BIT-discourse-2026-91122
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.