CVE-2021-29430 : What You Need to Know

Sydent is a reference Matrix identity server that allows large requests, leading to memory exhaustion and denial of service attacks. Learn more about the impact, technical details, and mitigation steps below.

Understanding CVE-2021-29430

This CVE involves a vulnerability in the Sydent server that could be exploited by malicious users to exhaust memory and disrupt services.

What is CVE-2021-29430?

Sydent does not limit request size, allowing attackers to send large requests causing memory exhaustion. This issue affects servers accepting registration from untrusted clients.

The Impact of CVE-2021-29430

The vulnerability poses a high risk with a CVSS base score of 7.5, enabling a denial of service attack via memory exhaustion.

Technical Details of CVE-2021-29430

The vulnerability involves improper input validation, leading to uncontrolled resource consumption.

Vulnerability Description

Sydent's lack of size limits for requests from HTTP clients and responses from remote servers can trigger memory exhaustion.

Affected Systems and Versions

Sydent versions prior to 2.3.0 are affected by this vulnerability.

Exploitation Mechanism

Attackers can exploit the vulnerability by sending large HTTP requests to exhaust server memory.

Mitigation and Prevention

Address the CVE-2021-29430 vulnerability with immediate actions and long-term security practices.

Immediate Steps to Take

Limit request sizes via an HTTP reverse-proxy and apply the provided patches to mitigate the risk.

Long-Term Security Practices

Ensure proper input validation and implement size limits for requests and responses in server configurations.

Patching and Updates

Update Sydent to versions 2.3.0 or higher to prevent memory exhaustion attacks.