CVE-2020-5403 : Security Advisory and Response

Reactor Netty HttpServer versions 0.9.3 and 0.9.4 are vulnerable to a URISyntaxException leading to premature connection closure.

Understanding CVE-2020-5403

This CVE involves a Denial of Service (DoS) vulnerability in Reactor Netty HTTP Server versions 0.9.3 and 0.9.4.

What is CVE-2020-5403?

CVE-2020-5403 is a vulnerability in Reactor Netty HttpServer that allows an attacker to cause a Denial of Service by exploiting a URISyntaxException, resulting in the premature closure of connections instead of generating a 400 response.

The Impact of CVE-2020-5403

The vulnerability has a CVSS base score of 6.5, indicating a medium severity issue. It can lead to a DoS condition with high availability impact.

Technical Details of CVE-2020-5403

This section provides more in-depth technical insights into the CVE.

Vulnerability Description

The vulnerability in Reactor Netty HttpServer versions 0.9.3 and 0.9.4 stems from a URISyntaxException that causes connections to close prematurely, impacting the server's response behavior.

Affected Systems and Versions

Product: Reactor Netty
Vendor: Pivotal
Affected Versions: 0.9.3 v0.9.3.RELEASE, 0.9.4 v0.9.4.RELEASE

Exploitation Mechanism

The vulnerability can be exploited by sending a specially crafted malformed URL to the affected server, triggering the premature closure of connections.

Mitigation and Prevention

Protecting systems from CVE-2020-5403 requires immediate actions and long-term security practices.

Immediate Steps to Take

Apply vendor-supplied patches or updates promptly.
Monitor network traffic for any suspicious activity targeting the vulnerability.
Implement network-level protections to filter out potentially malicious requests.

Long-Term Security Practices

Regularly update and patch software to address known vulnerabilities.
Conduct security assessments and penetration testing to identify and remediate weaknesses.
Stay informed about security advisories and best practices to enhance overall system security.

Patching and Updates

Ensure that the affected Reactor Netty versions (0.9.3 and 0.9.4) are updated to the latest secure releases provided by Pivotal.