CVE-2019-9900 : What You Need to Know

CVE-2019-9900 was published on April 25, 2019, and affects Envoy versions prior to 1.9.0. This vulnerability allows attackers to potentially bypass header matching rules and gain unauthorized access to resources.

Understanding CVE-2019-9900

CVE-2019-9900 is a medium-severity vulnerability with a CVSS base score of 6.5.

What is CVE-2019-9900?

When parsing HTTP/1.x header values, Envoy versions before 1.9.0 do not reject embedded zero characters (NUL, ASCII 0x0). This oversight enables attackers to craft header values containing embedded NUL characters, potentially leading to unauthorized resource access.

The Impact of CVE-2019-9900

Attack Vector: Network
Attack Complexity: High
Privileges Required: None
Confidentiality Impact: Low
Integrity Impact: Low
Availability Impact: Low
Scope: Changed
User Interaction: None

Technical Details of CVE-2019-9900

CVE-2019-9900 has the following technical details:

Vulnerability Description

Envoy versions prior to 1.9.0 do not reject embedded zero characters in HTTP/1.x header values, potentially allowing unauthorized access to resources.

Affected Systems and Versions

Affected Product: N/A
Affected Vendor: N/A
Affected Versions: All versions prior to 1.9.0

Exploitation Mechanism

Attackers can exploit this vulnerability by crafting header values with embedded NUL characters to bypass header matching rules.

Mitigation and Prevention

To address CVE-2019-9900, consider the following mitigation strategies:

Immediate Steps to Take

Update Envoy to version 1.9.0 or later to mitigate the vulnerability.
Monitor network traffic for any signs of exploitation.

Long-Term Security Practices

Regularly update and patch software to prevent known vulnerabilities.
Implement network security measures to detect and block malicious traffic.
Educate users and administrators on secure coding practices.

Patching and Updates

Apply patches and updates provided by Envoy to fix the vulnerability.