CVE-2018-16515

HIGHNVD 8.8

8.8

Matrix Synapse before 0.33.3.1 allows remote attackers to spoof events and possibly have unspecified other impacts by leveraging improper transaction and event signature validation.

CVSS v3: 8.8
EG Score: —
EPSS: 63.4%
KEV: Not listed

Published

September 18, 2018

Last Modified

November 21, 2024

References (6)

cve@mitrehttps://github.com/matrix-org/synapse/issues/3796#event-1833126269
cve@mitrehttps://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IRW7YR2H3ASUSYX4AO4KMY3FNVDNYW3P/
cve@mitrehttps://matrix.org/blog/2018/09/06/critical-security-update-synapse-0-33-3-1/
af854a3a-2127-422b-91ae-364da2661108https://github.com/matrix-org/synapse/issues/3796#event-1833126269
af854a3a-2127-422b-91ae-364da2661108https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IRW7YR2H3ASUSYX4AO4KMY3FNVDNYW3P/
af854a3a-2127-422b-91ae-364da2661108https://matrix.org/blog/2018/09/06/critical-security-update-synapse-0-33-3-1/

Affected Packages

(1 across 1 ecosystem)

PyPI(1)

Package	Vulnerable range	Fixed in	Dependents
matrix-synapse	—	0.33.2.1	—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

CWE-347Improper Verification of Cryptographic Signature

Data Freshness Timeline

(refreshed 6× in last 7d / 6× in last 30d)

Every time one of our enrichment pipelines (NVD, MITRE cvelistV5, EPSS, CISA KEV, GHSA, OSV, vendor advisories) ran against this CVE. Most recent first.

2026-05-27 13:38 UTCepss_batch
2026-05-27 13:38 UTCepss_batch
2026-05-26 13:42 UTCepss_batch
2026-05-26 13:42 UTCepss_batch
2026-05-26 07:17 UTCepss_batch
2026-05-26 07:17 UTCepss_batch

Frequently asked(5)

What is CVE-2018-16515?

CVE-2018-16515 is a high vulnerability published on September 18, 2018. Matrix Synapse before 0.33.3.1 allows remote attackers to spoof events and possibly have unspecified other impacts by leveraging improper transaction and event signature validation.

When was CVE-2018-16515 disclosed?

CVE-2018-16515 was first published in the National Vulnerability Database on September 18, 2018, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.

Is CVE-2018-16515 actively exploited?

CVE-2018-16515 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 63.4% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

What is the CVSS score of CVE-2018-16515?

CVE-2018-16515 has a CVSS v3 base score of 8.8 (NVD).

How do I remediate CVE-2018-16515?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2018-16515, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2018-16515

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