Synapse is a Matrix reference homeserver written in python (pypi package matrix-synapse). Matrix is an ecosystem for open federated Instant Messaging and VoIP. In Synapse before version 1.27.0, the password reset endpoint served via Synapse was vulnerable to cross-site scripting (XSS) attacks. The impact depends on the configuration of the domain that Synapse is deployed on, but may allow access to cookies and other browser data, CSRF vulnerabilities, and access to other resources served on the same domain or parent domains. This is fixed in version 1.27.0.
bugzilla.redhat.com/show_bug.cgi?id=1944135
github.com/matrix-org/synapse/commit/e54746bdf7d5c831eabe4dcea76a7626f1de73df https://github.com/matrix-org/synapse/pull/9200 https://github.com/matrix-org/synapse/releases/tag/v1.27.0 https://github.com/matrix-org/synapse/security/advisories/GHSA-246w-56m2-5899