CVE-2017-20290

Discourse < 1.9.0.beta13 Reflected XSS via /email/unsubscribed

Published Oct 22, 2026 CVSS 4.0 · 5.1 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Title Discourse < 1.9.0.beta13 Reflected XSS via /email/unsubscribed
First Time appeared Discourse
Discourse discourse
Weaknesses CWE-79
CPEs cpe:2.3:a:discourse:discourse:*:*:*:*:*:*:*:*
Vendors & Products Discourse
Discourse discourse
References
Metrics cvssV3_1

{'score': 6.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N'}

cvssV4_0

{'score': 5.1, 'vector': '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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Nov 5, 2026, 5:17 PM
Reserved
Oct 14, 2026, 8:25 PM
Status
Deferred
Published
Oct 22, 2026, 11:17 AM
Modified
Nov 5, 2026, 6:16 PM