Discourse up to 1.9.0.beta12 Email Unsubscription unsubscribed.html.erb email cross site scripting

Summaryinfo

A vulnerability, which was classified as problematic, was found in Discourse up to 1.9.0.beta12. The affected element is an unknown function of the file unsubscribed.html.erb of the component Email Unsubscription. Executing a manipulation of the argument email can lead to cross site scripting. This vulnerability only affects products that are no longer supported by the maintainer. This vulnerability is handled as CVE-2017-20290. The attack can be executed remotely. There is not any exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Discourse up to 1.9.0.beta12. It has been declared as problematic. This vulnerability affects some unknown functionality of the file unsubscribed.html.erb of the component Email Unsubscription. The manipulation of the argument email with an unknown input leads to a cross site scripting vulnerability. The CWE definition for the vulnerability is CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. As an impact it is known to affect integrity. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability was named CVE-2017-20290 since 10/14/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Successful exploitation requires user interaction by the victim. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1059.007 by the MITRE ATT&CK project.

Upgrading to version 1.9.0.beta13 eliminates this vulnerability.

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Productinfo

Type

• Chat Software

Name

• Discourse

Version

• 1.9.0.beta12

License

• open-source

Support

• end of life

Website

• Product: https://github.com/discourse/discourse/

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