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Not in CISA KEV
HIGH severity

CVE-2019-11842 — matrix-sydent

HIGH

CVE-2019-11842 is a high-severity (CVSS 7.5) CWE-338 vulnerability in matrix-sydent. A fix is available for matrix-sydent — see the affected versions and patch details below.

matrix-sydent and matrix-synapse Use Cryptographically Weak PRNG

Also known asGHSA-gwf7-vfjf-wf6xPYSEC-2019-185PYSEC-2026-2620
Published
Updated
Affected
2 pkgs
Patched
2 / 2
Exploits
None indexed
Exploitation data as of Nov 9, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.8%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs79th percentile — riskier than 79% of all scored CVEsHighest risk
0.00%0.77%1.53%2.30%0.5%1.8%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

2 pkgs affected
🐍matrix-sydent🐍matrix-synapse

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

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 Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
🐍PyPImatrix-sydentall versions1.0.3pip install --upgrade 'matrix-sydent==1.0.3'
🐍PyPImatrix-synapseall versions0.99.3.1pip install --upgrade 'matrix-synapse==0.99.3.1'

Affected Products

2 products · 2 configurations
Application
sydentmatrix
< 1.0.3
range
Application
synapsematrix
< 0.99.3.1
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for matrix-sydent, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update matrix-sydent to 1.0.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2019-11842 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

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.
O3 Security · Impact-Aware SCA

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CVE-2019-11842: matrix-sydent — Fixed in 1.0.3