CVE-2025-30355

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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTNIST
7.1 HIGH
NETWORK
LOW
LOW
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H
GitHub_MCNA
7.1 HIGH
NETWORK
LOW
LOW
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H
CISA-ADPADP
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Awaiting analysis
This vulnerability is currently awaiting analysis.
Base Score
CVSS 3.x
EPSS Score
Percentile: 84%
Debian logo
Debian Releases
Debian Product
Codename
matrix-synapse
sid
1.128.0-1
fixed
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
matrix-synapse
oracular
needs-triage
noble
needs-triage
jammy
needs-triage
focal
needs-triage
bionic
needs-triage
Common Weakness Enumeration
References
https://github.com/element-hq/synapse/commit/2277df2a1eb685f85040ef98fa21d41aa4cdd389
https://github.com/element-hq/synapse/releases/tag/v1.127.1
https://github.com/element-hq/synapse/security/advisories/GHSA-v56r-hwv5-mxg6