What is CVE-2019-11842?

CVE-2019-11842 is a high-severity vulnerability in Matrix Sydent, classified under Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG). CVSS score: 7.5/10. Published 2019-05-09.

How severe is CVE-2019-11842?

High severity. CVSS v3 base score is 7.5 out of 10.

Is CVE-2019-11842 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Vulnerability in Matrix Sydent

CVE-2019-11842

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.

Published 2019-05-09 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.018 (77.5th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 78th percentile — 77.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.018 · newest: 0.018 · change: +0.000

Affected products

Weakness classification (CWE)

CWE-338 — Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)

Public proof-of-concept exploits

ARPSyndicate/cvemon

References

matrix.org/blog/2019/05/03/security-updates-sydent-1-0-3-synapse-0-99-3-1-and-r… (Vendor Advisory)

Frequently asked questions

What is CVE-2019-11842?: CVE-2019-11842 is a high-severity vulnerability in Matrix Sydent, classified under Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG). CVSS score: 7.5/10. Published 2019-05-09.
How severe is CVE-2019-11842?: High severity. CVSS v3 base score is 7.5 out of 10.
Is CVE-2019-11842 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.