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CVE-2019-11842

matrix-sydent and matrix-synapse Use Cryptographically Weak PRNG

7.5 HighFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
None
Availability
None

Exploit likelihood

1.80%Up 1.4 points since Apr 14, 2021
90%50%10%1%

What each source reports

NVD Score used 7.5

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.

Record
CVE-2019-11842
CVSS 3.0
7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
CVSS 2.0
5.0 MediumAV:N/AC:L/Au:N/C:P/I:N/A:N
Weakness
CWE-338
Updated
2026-11-02
CVE List No score

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.

Record
CVE-2019-11842
Updated
2026-11-02
EUVDEUVD-2019-0082 No score

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.

Record
EUVD-2019-0082
Updated
2026-11-03
GitHub AdvisoriesGHSA-gwf7-vfjf-wf6x 8.7

matrix-sydent and matrix-synapse Use Cryptographically Weak PRNG

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.

Record
GHSA-gwf7-vfjf-wf6x
CVSS 4.0
8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
CVSS 3.0
7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Weakness
CWE-338
Updated
2026-11-02
OSV 7.5

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.

Record
CVE-2019-11842
CVSS 3.0
7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Updated
2026-11-02
OSVDEBIAN-CVE-2019-11842 7.5

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.

Record
DEBIAN-CVE-2019-11842
CVSS 3.0
7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Updated
2026-11-02
Show 5 moreShow less
OSVGHSA-gwf7-vfjf-wf6x 8.7

matrix-sydent and matrix-synapse Use Cryptographically Weak PRNG

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.

Record
GHSA-gwf7-vfjf-wf6x
CVSS 4.0
8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
CVSS 3.0
7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Weakness
CWE-338
Updated
2026-11-02
OSVPYSEC-2026-2620 8.7

matrix-sydent and matrix-synapse Use Cryptographically Weak PRNG

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.

Record
PYSEC-2026-2620
CVSS 4.0
8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
CVSS 3.0
7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Updated
2026-11-02
OSVUBUNTU-CVE-2019-11842 7.5

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.

Record
UBUNTU-CVE-2019-11842
CVSS 3.0
7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Updated
2026-11-02
OSVPYSEC-2019-185 No score

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.

Record
PYSEC-2019-185
Updated
2026-11-02
OSVUSN-6076-1 No score

matrix-synapse vulnerabilities

It was discovered that Synapse incorrectly handled certain inputs. If a user or an automated system were tricked into opening a specially crafted input file, a remote attacker could possibly use this issue to cause a denial of service. (CVE-2019-18835, CVE-2018-12291, CVE-2018-10657)

It was discovered that Synapse incorrectly handled certain inputs. If a user or an automated system were tricked into opening a specially crafted input file, a remote attacker could possibly use this issue to hijack the session. (CVE-2019-11842, CVE-2018-12423)

It was discovered that Synapse incorrectly handled certain inputs. If a user or an automated system were tricked into opening a specially crafted input file, a remote attacker could possibly use this issue to perform spoofing or user impersonation. (CVE-2019-5885, CVE-2018-16515)

Record
USN-6076-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
matrix-sydent
PyPI
 before 1.0.3
1.0.3
matrix-synapse
PyPI
 before 0.99.3.1
0.99.3.1
matrix-synapse
PyPI
 before 0.99.3.1, plus listed versions
0.33.50.33.5.10.33.60.33.6rc10.33.7
Show 23 moreShow less
0.33.7rc10.33.7rc20.33.80.33.8rc20.33.90.34.00.34.0.10.34.0rc10.34.0rc20.34.1.10.99.00.99.0rc10.99.0rc20.99.0rc30.99.0rc40.99.10.99.1.10.99.1rc10.99.1rc20.99.20.99.2rc10.99.30.99.3rc1
0.99.3.1
matrix-synapse
Ubuntu:Pro:18.04:LTS
 before 0.24.0+dfsg-1ubuntu0.1~esm1, plus listed versions
0.19.2+dfsg-60.24.0+dfsg-1
0.24.0+dfsg-1ubuntu0.1~esm1
matrix-synapse
Ubuntu:Pro:18.04:LTS
From an advisory covering 7 CVEs
 before 0.24.0+dfsg-1ubuntu0.1~esm1, plus listed versions
0.19.2+dfsg-60.24.0+dfsg-1
0.24.0+dfsg-1ubuntu0.1~esm1

History

History
RecordedChangedSources
affected, facts
affected
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2019-11842 is a high vulnerability (CVSS 7.5) in Matrix Sydent, published May 9, 2019. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.80%, the 78th percentile. Fixed in matrix-sydent 1.0.3.

References

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