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.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - 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.
    (CVE-2025-30355)

Note that Nessus relies on the presence of the package as reported by the vendor.

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - 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.
    (CVE-2025-30355)

ID	Name	Product	Family	Severity
255447	Linux Distros Unpatched Vulnerability : CVE-2025-30355	Nessus	Misc.	high
427518	Alpine: multiple synapse packages: security update to 1.127.1-r0	Tenable Cloud Security	Alpine Linux Local Security Checks	high
427518	Alpine: multiple synapse packages: security update to 1.127.1-r0	Tenable Self-Hosted Container Security	Alpine Linux Local Security Checks	high
421243	SCA: security update for matrix-synapse (GHSA-v56r-hwv5-mxg6)	Tenable Cloud Security	SCA Checks	high
421243	SCA: security update for matrix-synapse (GHSA-v56r-hwv5-mxg6)	Tenable Self-Hosted Container Security	SCA Checks	high

Detections

Analytics

CVE-2025-30355

high

Tenable Plugins

high

high

high

high

high