Cross-site Scripting (XSS) via topic titles when CSP disabled in Discourse
Priority LOW 24CWE-79Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- Required
- Attack complexity
- Low
- Impact type
- Cross-site scripting
- Confidentiality · integrity · availability
- Low · Low · None
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-79.
Summary
Discourse is an open source platform for community discussion. In affected versions with some combinations of plugins, and with CSP disabled, activity streams in the user's profile page may be vulnerable to XSS. This has been patched in the latest version of Discourse core. Users are advised to upgrade. Users unable to upgrade should ensure CSP is enabled.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00279 20th percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- 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 | stable: < 3.3.3; tests-passed: < 3.4.0.beta4 | — | No fix listed | CNA |
- discourse Vendordiscourse Affected stable: < 3.3.3; tests-passed: < 3.4.0.beta4 Fixed in — No fix listed CNA
CPE configurations NVD · 5
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:discourse:discourse:*:*:*:*:stable:*:*:* | before 3.3.3 | Vulnerable | discourse |
| cpe:2.3:a:discourse:discourse:*:*:*:*:beta:*:*:* | before 3.4.0 | Vulnerable | discourse |
| cpe:2.3:a:discourse:discourse:3.4.0:beta1:*:*:beta:*:*:* | 3.4.0 beta1 | Vulnerable | discourse |
| cpe:2.3:a:discourse:discourse:3.4.0:beta2:*:*:beta:*:*:* | 3.4.0 beta2 | Vulnerable | discourse |
| cpe:2.3:a:discourse:discourse:3.4.0:beta3:*:*:beta:*:*:* | 3.4.0 beta3 | Vulnerable | discourse |
- cpe:2.3:a:discourse:discourse:*:*:*:*:stable:*:*:* Versions before 3.3.3 Vulnerable ·discourse
- cpe:2.3:a:discourse:discourse:*:*:*:*:beta:*:*:* Versions before 3.4.0 Vulnerable ·discourse
- cpe:2.3:a:discourse:discourse:3.4.0:beta1:*:*:beta:*:*:* Versions 3.4.0 beta1 Vulnerable ·discourse
- cpe:2.3:a:discourse:discourse:3.4.0:beta2:*:*:beta:*:*:* Versions 3.4.0 beta2 Vulnerable ·discourse
- cpe:2.3:a:discourse:discourse:3.4.0:beta3:*:*:beta:*:*:* Versions 3.4.0 beta3 Vulnerable ·discourse
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2024-53266
References
More Discourse vulnerabilities
- TI-2021-19656 Denial of Service in discourse CVSS 3.1MEDIUM 6.8
- 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
Sources
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences