CVE-2025-30355

moderate-risk
Published 2025-03-27

Synapse is an open source Matrix homeserver implementation. A malicious server can craft events which, when received, prevent Synapse version up to 1.127.0 from federating with other servers. The vulnerability has been exploited in the wild and has been fixed in Synapse v1.127.1. No known workarounds are available.

Do I need to act?

~
7.5% chance of exploitation in next 30 days
EPSS score — moderate exploit probability
-
Not on CISA KEV list
No confirmed active exploitation reported to CISA
?
Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
7
CVSS 7.1/10 High
NETWORK / LOW complexity

Affected Products (1)

Affected Vendors

Matrix

References (3)

Patch https://github.com/element-hq/synapse/commit/2277df2a1eb685f85040ef98fa21d41aa4c...
Release Notes https://github.com/element-hq/synapse/releases/tag/v1.127.1
Vendor Advisory https://github.com/element-hq/synapse/security/advisories/GHSA-v56r-hwv5-mxg6
40
/ 100
moderate-risk
Severity 25/34 · High
Exploitability 10/34 · Low
Exposure 5/34 · Minimal