CVE-2019-18802 : Vulnerability Insights and Analysis

A vulnerability in Envoy version 1.12.0 allows untrusted remote clients to bypass matchers by including extra spaces after HTTP headers.

Understanding CVE-2019-18802

What is CVE-2019-18802?

This CVE identifies a flaw in Envoy 1.12.0 that mishandles HTTP headers with trailing spaces, enabling attackers to evade specific matchers.

The Impact of CVE-2019-18802

The vulnerability permits malicious actors to manipulate headers, potentially leading to security bypasses and unauthorized access.

Technical Details of CVE-2019-18802

Vulnerability Description

Envoy incorrectly distinguishes between strings with and without trailing spaces in HTTP headers, allowing for evasion of security measures.

Affected Systems and Versions

Product: Envoy
Vendor: N/A
Version: 1.12.0

Exploitation Mechanism

Attackers can exploit this issue by appending spaces after HTTP headers, such as the Host header, to deceive Envoy's matching mechanisms.

Mitigation and Prevention

Immediate Steps to Take

Update Envoy to a patched version that addresses this vulnerability.
Monitor and restrict incoming HTTP headers to prevent manipulation.

Long-Term Security Practices

Implement strict input validation to detect and block malformed headers.
Regularly review and update security configurations to mitigate similar risks.

Patching and Updates

Apply security patches provided by Envoy to fix the vulnerability and enhance system security.