CVE-2019-11842: Matrix Sydent

High severity, CVSS 7.5. EPSS: 1.8% chance of exploitation in the next 30 days.

An issue was discovered in Matrix Sydent before 1.0.3 and Synapse before 0.99.3.1. Random number generation is mishandled, which makes it easier for attackers to predict a Sydent authentication token or a Synapse random ID.

Affected products

• Matrix Sydent: before 1.0.3 (fixed in 1.0.3)
• Matrix Synapse: before 0.99.3.1 (fixed in 0.99.3.1)

Published 2019-05-09. Last modified 2026-06-17.