Cross-site Scripting (XSS) The advisory has been revoked - it doesn't affect any version of package matrix-synapse (opens in a new tab)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-DEBIAN13-MATRIXSYNAPSE-5883079
- published20 Oct 2020
- disclosed19 Oct 2020
Introduced: 19 Oct 2020
CVE-2020-26891 (opens in a new tab)Amendment
The Debian security team deemed this advisory irrelevant for Debian:13.
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.
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