Impact
Gotify exposes an outdated instance of the Swagger UI API documentation frontend at /docs which is susceptible to reflected XSS attacks when loading external Swagger config files.
Specifically, the DOMPurify version included with this version of Swagger UI is vulnerable to a rendering XSS incorporating the mutation payload detailed in CVE-2020-26870 which was patched in 2021. This is further tracked in the GitHub Advisory Database as GHSA-QRMM-W75W-3WPX.
An attacker can execute arbitrary JavaScript and potentially take over the account of the user that clicked the link. Keep in mind, the Gotify UI won’t natively expose such a malicious link, so an attacker has to get the user to open the malicious link in a context outside of Gotify.
Patches
The vulnerability has been fixed in version 2.2.3.
References
https://github.com/gotify/server/pull/541
References
- https://github.com/gotify/server/security/advisories/GHSA-3244-8mff-w398
- https://github.com/gotify/server/pull/541
- https://research.securitum.com/mutation-xss-via-mathml-mutation-dompurify-2-0-17-bypass/
- https://www.vidocsecurity.com/blog/hacking-swagger-ui-from-xss-to-account-takeovers/
- https://github.com/advisories/GHSA-3244-8mff-w398