CVE-2017-20290
Discourse < 1.9.0.beta13 Reflected XSS via /email/unsubscribed
CVSS Score
6.1
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-79 |
| Vendor | discourse |
| Product | discourse |
| Published | Oct 22, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None
Affected Versions
Discourse / Discourse
1.9.0.beta2 < 1.9.0.beta13
References
github.com: https://github.com/discourse/discourse/commit/a6f2533d38 github.com: https://github.com/discourse/discourse/commit/6e37f09b19 github.com: https://github.com/projectdiscovery/nuclei-templates/blob/main/http/vulnerabilities/other/discourse-xss.yaml vulncheck.com: https://www.vulncheck.com/advisories/discourse-1.9.0-beta13-reflected-xss-via-email-unsubscribed
Credits
🔍 The Shadowserver Foundation