CVE-2017-20290

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

MEDIUM
6.1
CVSS Score
Published: October 22, 2026 at 10:57 AM UTC
Updated: October 22, 2026 at 11:17 AM UTC
1 product affected across 1 vendorDiscourse

Using Discourse by Discourse?

Get instant alerts when new vulnerabilities affect Discourse - before attackers find them.

Real-time alertsTrack your software stackFree plan available
Severity
MEDIUM6.1
Exploit prediction
EPSS 0.3%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

1.9.0.beta2

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

CVSS

6.1MEDIUMVulnCheck
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-79

Get alerted

Stop reading CVE feeds looking for your own stack

Track the products you run and VulnTracker tells you when a new CVE affects them — with what is known about fixing it, and nothing about the rest.

Free plan, no card