VulnerabilityAnalyzed
CVE-2025-30355
A malicious server can craft events which, when received, prevent Synapse version up to 1.127.0 from federating with other servers.
HIGH 7.5EPSS 1.18%
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (1.18%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
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.
- CVSS 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 1.18% probability · 66th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-20
- Affected
- matrix/synapse
- Source
- security-advisories@github.com
References
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.