CVE-2017-20290
Discourse < 1.9.0.beta13 Reflected XSS via /email/unsubscribed
- State
- Published
- Severity
- 5.1 Medium
- Published
- Oct 22, 2026
- Updated
- Oct 22, 2026
- Reserved
- Oct 14, 2026
Description
Discourse 1.9.0.beta2 before 1.9.0.beta13 contains a reflected cross-site scripting vulnerability that allows unauthenticated attackers to inject scripts through the email parameter of /email/unsubscribed. Attackers can craft GET requests with SVG onload payloads, which unsubscribed.html.erb renders unescaped via html_safe, executing JavaScript in victims' browsers. Exploitation evidence was first observed by the Shadowserver Foundation on 2023-10-19.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 5.1 Medium | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N | VulnCheck |
| 3.1 | 6.1 Medium | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N | VulnCheck |
Weaknesses
- CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Products
| Product | Versions |
|---|---|
DiscourseDiscourse |
|
References
- Fix Commitpatch
- Introducing Committechnical-descriptionpatch
- Nuclei Templatetechnical-description
- VulnCheck Advisory: Discourse < 1.9.0.beta13 Reflected XSS via /email/unsubscribedthird-party-advisory
Every record here comes from the CVE Program’s CVE List. © 1999–2026 The MITRE Corporation. CVE is a registered trademark of The MITRE Corporation. The records are reproduced under the CVE Program terms of use.