GHSA-3244-8mff-w398 Reflected XSS in Gotify's /docs via import of outdated Swagger UI

• Go github.com/gotify/server: < 2.2.3 → fixed in 2.2.3

Impact Gotify exposes an outdated instance of the Swagger UI API documentation frontend at `/docs` which is susceptible to reflected XSS attacks when loading external Swagger config files.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