In the SPNEGO HTTP Authentication Module for nginx (spnego-http-auth-nginx-module) before version 1.1.1, basic Authentication can be bypassed using a malformed username. This affects users of spnego-http-auth-nginx-module that have enabled basic authentication. This vulnerability allows an attacker to exploit the authentication mechanism, potentially gaining unauthorized access to protected resources. The vulnerability has been assigned a CVSS score of 5.3, indicating a medium severity level.
Risk to organizations includes exposure to unauthorized access when basic authentication is enabled. The vulnerability is due to insufficient validation of username input, allowing crafted usernames to bypass authentication controls. Organizations should prioritize patching immediately by updating to version 1.1.1 of the spnego-http-auth-nginx-module. As an alternative, one may disable basic authentication until the patch can be applied.
The vulnerability was published on March 8, 2021, and has been modified in the database. The exploitation status shows that there are currently no known exploits for this vulnerability, but organizations should remain vigilant and monitor their systems for any signs of compromise.
Given the potential impact of this vulnerability, organizations using the spnego-http-auth-nginx-module should evaluate their risk posture and take immediate action to remediate.
Vulnerability Details
This vulnerability allows bypassing basic authentication in the SPNEGO HTTP Authentication Module for nginx. It was disclosed as a medium severity issue with a CVSS score of 5.3. The vulnerability affects all versions prior to 1.1.1 of the spnego-http-auth-nginx-module. The flaw can lead to unauthorized access to resources protected by basic authentication.
Technical Analysis
The root cause of this vulnerability is a lack of proper validation of username inputs within the authentication module. Attackers may leverage malformed usernames to bypass authentication checks. The attack vector is network-based, and the attack complexity is low, requiring no privileges or user interaction. The impact includes low confidentiality exposure, with no integrity or availability impact.
Risk & Impact Analysis
The real-world deployment risk of this vulnerability is significant, particularly for organizations relying on the spnego-http-auth-nginx-module for authentication. The potential for unauthorized access could lead to data breaches or other security incidents. Organizations should assess the urgency based on the CVSS score and prioritize remediation accordingly.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
All versions prior to vendor patch 1.1.1 of the spnego-http-auth-nginx-module are affected. Organizations using this module should ensure they upgrade to the latest version to mitigate this vulnerability.
Mitigation & Remediation
Organizations should prioritize patching immediately by upgrading to version 1.1.1 of the spnego-http-auth-nginx-module. If immediate upgrading is not feasible, a workaround is to disable basic authentication.
Detection Guidance
Monitor logs for anomalies related to authentication failures and unexpected access attempts. Ensure that any attempts to authenticate with malformed usernames are logged and reviewed.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2021-21335 lies in its demonstration of how small oversights in input validation can lead to significant vulnerabilities. Security teams should take this opportunity to review their authentication mechanisms, ensuring robust validation practices are in place.
This vulnerability represents a common failure in web application security. Organizations must learn from such incidents to strengthen their defenses against similar attacks in the future.
For further information on securing web applications, organizations may refer to best practices in our web application penetration testing guide, which provides comprehensive strategies for mitigating vulnerabilities.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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