CVE-2021-21332

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.

• CWE-79
• CWE-79

• https://github.com/matrix-org/synapse/commit/e54746bdf7d5c831eabe4dcea76a7626f1de73dfPatch, Third Party Advisory
• https://github.com/matrix-org/synapse/pull/9200Patch, Third Party Advisory
• https://github.com/matrix-org/synapse/releases/tag/v1.27.0Third Party Advisory
• https://github.com/matrix-org/synapse/security/advisories/GHSA-246w-56m2-5899Third Party Advisory
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TNNAJOZNMVMXM6AS7RFFKB4QLUJ4IFEY/
• https://github.com/matrix-org/synapse/commit/e54746bdf7d5c831eabe4dcea76a7626f1de73dfPatch, Third Party Advisory
• https://github.com/matrix-org/synapse/pull/9200Patch, Third Party Advisory
• https://github.com/matrix-org/synapse/releases/tag/v1.27.0Third Party Advisory
• https://github.com/matrix-org/synapse/security/advisories/GHSA-246w-56m2-5899Third Party Advisory
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TNNAJOZNMVMXM6AS7RFFKB4QLUJ4IFEY/

Published

Mar 26, 2021

Last Modified

Jun 17, 2026

Status

Modified

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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