Cross-site Scripting (XSS) Affecting matrix-synapse package, versions <1.21.1-1
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Test your applications- Snyk ID SNYK-DEBIANUNSTABLE-MATRIXSYNAPSE-1019436
- published 20 Oct 2020
- disclosed 19 Oct 2020
Introduced: 19 Oct 2020
CVE-2020-26891 Open this link in a new tabHow to fix?
Upgrade Debian:unstable matrix-synapse to version 1.21.1-1 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream matrix-synapse package and not the matrix-synapse package as distributed by Debian.
See How to fix? for Debian:unstable relevant fixed versions and status.
AuthRestServlet in Matrix Synapse before 1.21.0 is vulnerable to XSS due to unsafe interpolation of the session GET parameter. This allows a remote attacker to execute an XSS attack on the domain Synapse is hosted on, by supplying the victim user with a malicious URL to the /_matrix/client/r0/auth//fallback/web or /_matrix/client/unstable/auth//fallback/web Synapse endpoints.
References
- https://security-tracker.debian.org/tracker/CVE-2020-26891
- https://github.com/matrix-org/synapse/security/advisories/GHSA-3x8c-fmpc-5rmq
- https://github.com/matrix-org/synapse/pull/8444
- https://github.com/matrix-org/synapse/releases
- https://github.com/matrix-org/synapse/releases/tag/v1.21.2
- https://matrix.org/blog/2020/10/15/synapse-1-21-2-released-and-security-advisory