How to fix CVE-2025-30355?

Within 7 days: Identify all affected systems and apply vendor patches promptly. Vendor patch is available.

Is Synapse affected by CVE-2025-30355?

Organizations using Synapse face moderate risk from CVE-2025-30355, a input validation vulnerability rated CVSS 7.1. Exploitation could compromise the security of affected deployments. A patch is available and should be applied as part of regular vulnerability management.

Synapse CVE-2025-30355

HIGH

Improper Input Validation (CWE-20)

2025-03-27 [email protected]

Information Disclosure Synapse Suse

7.1

CVSS 3.1

CVSS VectorNVD

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

Low

Availability

High

Lifecycle Timeline

Analysis Generated

Mar 28, 2026 - 18:33 vuln.today

Patch released

Mar 28, 2026 - 18:33 nvd

Patch available

CVE Published

Mar 27, 2025 - 01:15 nvd

HIGH 7.1

DescriptionNVD

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.

AnalysisAI

Synapse is an open source Matrix homeserver implementation. Rated high severity (CVSS 7.1), this vulnerability is remotely exploitable, low attack complexity.

Technical ContextAI

This vulnerability is classified under CWE-20. 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. Affected products include: Matrix Synapse. Version information: up to 1.127.0.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.

Vendor StatusVendor

CVE-2025-30355 vulnerability details – vuln.today

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