CVE-2019-18838 : Security Advisory and Response

In Envoy 1.12.0, a vulnerability has been identified that can lead to a NULL pointer dereference issue, causing the Envoy process to terminate unexpectedly.

Understanding CVE-2019-18838

This CVE involves a specific issue in Envoy 1.12.0 related to malformed HTTP requests without a Host header.

What is CVE-2019-18838?

When Envoy receives a malformed HTTP request without a Host header, it generates an "Invalid request" response. This response passes through the encoder filter chain and can trigger a NULL pointer dereference if an encoder filter accesses route manager APIs that require the Host header.

The Impact of CVE-2019-18838

The vulnerability can result in the unexpected termination of the Envoy process, potentially leading to service disruption or denial of service.

Technical Details of CVE-2019-18838

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

Vulnerability Description

The issue in Envoy 1.12.0 allows for a NULL pointer dereference when certain conditions with malformed HTTP requests occur, leading to process termination.

Affected Systems and Versions

Affected Version: Envoy 1.12.0
Systems: Any system running Envoy 1.12.0

Exploitation Mechanism

Malformed HTTP requests without a Host header trigger the vulnerability
Encoder filter chain configuration allows the issue to manifest
Accessing route manager APIs requiring the Host header leads to NULL pointer dereference

Mitigation and Prevention

To address CVE-2019-18838, follow these mitigation strategies:

Immediate Steps to Take

Update Envoy to a patched version that addresses the vulnerability
Implement strict input validation to prevent malformed HTTP requests

Long-Term Security Practices

Regularly monitor Envoy security advisories and updates
Conduct security audits to identify and address potential vulnerabilities

Patching and Updates

Apply patches provided by Envoy to fix the vulnerability
Stay informed about security best practices and updates from Envoy