CVE-2025-30355

Synapse vulnerable to federation denial of service via malformed events

Published: Mar 27, 2025Updated: Aug 26, 2025 Sources: CVE List NVD GHSACWE-20

7.1HIGH

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.

No summary for this CVE yet.

CVSS Vector Breakdown

Exploitability

AV:NAttack Vector

Network

AC:LAttack Complexity

Low

PR:LPrivileges Required

Low

UI:NUser Interaction

None

Scope

S:UScope

Unchanged

Impact

C:NConfidentiality

None

I:LIntegrity

Low

A:HAvailability

High

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Weaknesses

CWE-20 NVD-CWE-noinfo

Affected Products

matrix

oss-project·GBaka synapse, matrix irc bridge, javascript sdk

synapseOn-premWeb App

Communications / messaging-chat

package-ecosystem

oss-project

synapseMixed

Communications / messaging-chat

Exploitability

Official Patch Available

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Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

1 technique

Initial Access

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References

https://github.com/element-hq/synapse/commit/2277df2a1eb685f85040ef98fa21d41aa4cdd389

github.com

https://github.com/element-hq/synapse/releases/tag/v1.127.1

github.com

https://github.com/element-hq/synapse/security/advisories/GHSA-v56r-hwv5-mxg6

github.com

and 2 more references View all →

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