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CVE-2019-11842· NVD / CVE Program· CNA mitre

An issue was discovered in Matrix Sydent before 1.0.3 and Synapse before 0.99.3.1.

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.

HighCVSS 7.5 · v3.0—No exploit Fix available
Published
May 9, 2019
Updated
Jun 16, 2026
EPSS
1.8% · 78th percentile
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Report tools

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Action score

31

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 1.8%

Noroxi analysis

No Noroxi analysis for this record yet

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Affected systems

VendorProduct
matrixsydent
matrixsynapse

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • matrix sydentbefore 1.0.3
  • matrix synapsebefore 0.99.3.1

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:14matrix-synapsebefore 0.99.2-50.99.2-5
PyPImatrix-sydentbefore 1.0.31.0.3
PyPImatrix-synapsebefore 0.99.3.10.99.3.1

Same product

matrix: all records

Other highest-scoring records for the same primary product.

  • CVE-2021-29430Denial of service attack via memory exhaustion
    31Monitor
  • CVE-2021-29431SSRF in Sydent due to missing validation of hostnames
    26Monitor
  • CVE-2019-11340util/emailutils.py in Matrix Sydent before 1.0.2 mishandles registration restrictions that are based on e-mail domain, if the allowed_local_
    24Monitor
  • CVE-2021-29432Malicious users could control the content of invitation emails
    22Monitor
  • CVE-2023-38686Sydent does not verify email server certificates
    21Monitor
  • CVE-2021-29433Denial of service (via resource exhaustion) due to improper input validation
    17Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
debian:matrix-synapse0.99.2-5 · Debian:14Package registry (OSV)
PyPI:matrix-sydent1.0.3Package registry (OSV)
PyPI:matrix-synapse0.99.3.1Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
none
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
None
Availability impact
None

Weakness class (CWE)

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

CVSS vector

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records