CVE-2019-18835 : What You Need to Know

Matrix Synapse before version 1.5.0 mishandles signature checking on certain federation APIs, potentially leading to events being improperly signed or originating from unexpected servers.

Understanding CVE-2019-18835

What is CVE-2019-18835?

Prior to version 1.5.0, Matrix Synapse has a vulnerability in handling signature verification on specific federation APIs, which could result in events not being correctly signed or originating from anticipated servers.

The Impact of CVE-2019-18835

This vulnerability could allow malicious actors to send events through certain endpoints without proper verification, potentially leading to unauthorized access or data manipulation.

Technical Details of CVE-2019-18835

Vulnerability Description

Matrix Synapse before version 1.5.0 mishandles signature verification on federation APIs, specifically /send_join, /send_leave, and /invite endpoints.

Affected Systems and Versions

Product: Not applicable
Vendor: Not applicable
Versions affected: Not applicable

Exploitation Mechanism

The vulnerability can be exploited by sending events through the vulnerable endpoints without proper signing, allowing attackers to manipulate data or gain unauthorized access.

Mitigation and Prevention

Immediate Steps to Take

Upgrade Matrix Synapse to version 1.5.0 or later to mitigate the vulnerability.
Monitor network traffic for any suspicious activity related to the affected endpoints.

Long-Term Security Practices

Regularly update and patch software to address known vulnerabilities.
Implement network segmentation and access controls to limit exposure to potential threats.

Patching and Updates

Ensure timely installation of security patches and updates provided by Matrix Synapse to address vulnerabilities.