Denial of Service in discourse
Priority MEDIUM 63CWE-20Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- Required
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA.
Summary
Discourse is an open source platform for community discussion. In affected versions admins users can trigger a Denial of Service attack via the `/message-bus/_diagnostics` path. The impact of this vulnerability is greater on multisite Discourse instances (where multiple forums are served from a single application server) where any admin user on any of the forums are able to visit the `/message-bus/_diagnostics` path. The problem has been patched. Please upgrade to 2.8.0.beta10 or 2.7.12. No workarounds for this issue exist.
Why it matters now
Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00855 58th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed discourse (discourse): 2.7.12, 2.8.0.beta10
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| discourse | discourse | before 2.7.12; 2.8.0.beta to before 2.8.0.beta10 | 2.7.12, 2.8.0.beta10 | Patch available | CNA |
- discourse Vendordiscourse Affected before 2.7.12; 2.8.0.beta to before 2.8.0.beta10 Fixed in 2.7.12, 2.8.0.beta10 Patch available CNA
CPE configurations NVD · 10
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:discourse:discourse:*:*:*:*:*:*:*:* | before 2.7.12 | Vulnerable | discourse |
| cpe:2.3:a:discourse:discourse:2.8.0:beta1:*:*:*:*:*:* | 2.8.0 beta1 | Vulnerable | discourse |
| cpe:2.3:a:discourse:discourse:2.8.0:beta2:*:*:*:*:*:* | 2.8.0 beta2 | Vulnerable | discourse |
| cpe:2.3:a:discourse:discourse:2.8.0:beta3:*:*:*:*:*:* | 2.8.0 beta3 | Vulnerable | discourse |
| cpe:2.3:a:discourse:discourse:2.8.0:beta4:*:*:*:*:*:* | 2.8.0 beta4 | Vulnerable | discourse |
| cpe:2.3:a:discourse:discourse:2.8.0:beta5:*:*:*:*:*:* | 2.8.0 beta5 | Vulnerable | discourse |
| cpe:2.3:a:discourse:discourse:2.8.0:beta6:*:*:*:*:*:* | 2.8.0 beta6 | Vulnerable | discourse |
| cpe:2.3:a:discourse:discourse:2.8.0:beta7:*:*:*:*:*:* | 2.8.0 beta7 | Vulnerable | discourse |
| cpe:2.3:a:discourse:discourse:2.8.0:beta8:*:*:*:*:*:* | 2.8.0 beta8 | Vulnerable | discourse |
| cpe:2.3:a:discourse:discourse:2.8.0:beta9:*:*:*:*:*:* | 2.8.0 beta9 | Vulnerable | discourse |
- cpe:2.3:a:discourse:discourse:*:*:*:*:*:*:*:* Versions before 2.7.12 Vulnerable ·discourse
- cpe:2.3:a:discourse:discourse:2.8.0:beta1:*:*:*:*:*:* Versions 2.8.0 beta1 Vulnerable ·discourse
- cpe:2.3:a:discourse:discourse:2.8.0:beta2:*:*:*:*:*:* Versions 2.8.0 beta2 Vulnerable ·discourse
- cpe:2.3:a:discourse:discourse:2.8.0:beta3:*:*:*:*:*:* Versions 2.8.0 beta3 Vulnerable ·discourse
- cpe:2.3:a:discourse:discourse:2.8.0:beta4:*:*:*:*:*:* Versions 2.8.0 beta4 Vulnerable ·discourse
- cpe:2.3:a:discourse:discourse:2.8.0:beta5:*:*:*:*:*:* Versions 2.8.0 beta5 Vulnerable ·discourse
- cpe:2.3:a:discourse:discourse:2.8.0:beta6:*:*:*:*:*:* Versions 2.8.0 beta6 Vulnerable ·discourse
- cpe:2.3:a:discourse:discourse:2.8.0:beta7:*:*:*:*:*:* Versions 2.8.0 beta7 Vulnerable ·discourse
- cpe:2.3:a:discourse:discourse:2.8.0:beta8:*:*:*:*:*:* Versions 2.8.0 beta8 Vulnerable ·discourse
- cpe:2.3:a:discourse:discourse:2.8.0:beta9:*:*:*:*:*:* Versions 2.8.0 beta9 Vulnerable ·discourse
Remediation
- Fix · CNA discourse (discourse) Fixed in 2.7.12, 2.8.0.beta10
Timeline
- 2026-10-02 Threatist record created from CVE-2021-43850
References
More Discourse vulnerabilities
- TI-2024-36150 Potential Backup file leaked via Nginx in Discourse CVSS 3.1HIGH 7.5
- TI-2021-18002 RCE via malicious SNS subscription payload CVSS 3.1CRITICAL 10.0
- TI-2026-24651 Discourse: Open redirect via `sso_destination_url` cookie in `enter` CVSS 4.0MEDIUM 5.1
- TI-2026-22278 Discourse leaks private topic title and post excerpt via user action API endpoint CVSS 4.0HIGH 8.7
- TI-2023-24152 Unauthenticated access to new private chat messages in Discourse CVSS 3.1HIGH 7.5
- TI-2024-33232 Bypass of Discourse Connect using other login paths if enabled in Discourse CVSS 3.1CRITICAL 9.1
Sources
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences