Is CVE-2017-20290 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2017-20290 being exploited in the wild.

How severe is CVE-2017-20290?

Medium severity, with a CVSS score of 6.1, published 22 October 2026.

Which products and versions are affected?

Discourse 1.9.0.beta2 to before 1.9.0.beta13.

Is there a fix for CVE-2017-20290?

Yes: fixed in 1.9.0.beta13. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2017-20290 attacked?

It is attacked over the network.

Am I affected by CVE-2017-20290?

Check whether you run Discourse at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2017-20290: Discourse reflected cross-site scripting in email unsubscribe

CVE-2017-20290 · Severity: medium · CVSS 6.1 · Published 2026-10-22

Discourse, a community discussion platform, contains a reflected cross-site scripting (XSS) vulnerability in its email unsubscribe page that allows unauthenticated attackers to inject malicious scripts. An attacker can craft a malicious link that, when clicked by a user, executes arbitrary JavaScript in the victim's browser, potentially stealing session cookies, credentials, or performing actions on behalf of the user.

Technologies: Discourse. Vendors: Discourse.

Quick answers

Is CVE-2017-20290 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2017-20290 being exploited in the wild.
How severe is CVE-2017-20290?: Medium severity, with a CVSS score of 6.1, published 22 October 2026.
Which products and versions are affected?: Discourse 1.9.0.beta2 to before 1.9.0.beta13.
Is there a fix for CVE-2017-20290?: Yes: fixed in 1.9.0.beta13. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2017-20290 attacked?: It is attacked over the network.
Am I affected by CVE-2017-20290?: Check whether you run Discourse at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

Fixed in: 1.9.0.beta13

Technical details

A reflected XSS vulnerability exists in the /email/unsubscribed endpoint where the email parameter is rendered unescaped via html_safe in the unsubscribed.html.erb template. Unauthenticated attackers can inject SVG onload payloads through crafted GET requests. The vulnerability was fixed by adding validation to raise Discourse::NotFound if the email parameter does not correspond to a valid user.

Affected products

Discourse Discourse 1.9.0.beta2 to before 1.9.0.beta13

Timeline

2026-10-22: disclosed
2023-10-19: exploited: Exploitation evidence observed by Shadowserver Foundation

References

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