CVE-2018-16515

Severity: high (CVSS 8.8 v3.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2018-09-18 · updated 2026-06-17
Weakness: CWE-347

Description

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.

Affected products

Debian Linux: 8.0
matrix-org synapse: before 0.33.3.1 — fixed in 0.33.3.1

How to fix

Upgrade to a fixed version: matrix-org synapse 0.33.3.1. Check the vendor advisory for mitigations.

References

https://github.com/matrix-org/synapse/issues/3796#event-1833126269
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IRW7YR2H3ASUSYX4AO4KMY3FNVDNYW3P/
https://matrix.org/blog/2018/09/06/critical-security-update-synapse-0-33-3-1/
https://github.com/matrix-org/synapse/issues/3796#event-1833126269
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IRW7YR2H3ASUSYX4AO4KMY3FNVDNYW3P/
https://matrix.org/blog/2018/09/06/critical-security-update-synapse-0-33-3-1/

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