CVE-2017-3167 in macOS
Summary
by MITRE
In Apache httpd 2.2.x before 2.2.33 and 2.4.x before 2.4.26, use of the ap_get_basic_auth_pw() by third-party modules outside of the authentication phase may lead to authentication requirements being bypassed.
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Analysis
by VulDB Data Team • 11/04/2025
The vulnerability identified as CVE-2017-3167 affects Apache HTTP Server versions prior to 2.2.33 and 2.4.26, representing a critical flaw in the server's authentication handling mechanism. This issue stems from improper implementation of the ap_get_basic_auth_pw() function within third-party modules, which can be invoked outside the standard authentication phase of request processing. The flaw creates a significant security gap that allows malicious actors to bypass authentication requirements that should normally be enforced during access control checks.
The technical root cause of this vulnerability lies in the improper timing and context of authentication function calls within the Apache module architecture. When third-party modules invoke ap_get_basic_auth_pw() outside of the proper authentication phase, the server fails to validate whether the authentication process has been properly initiated or completed. This function is designed to extract basic authentication credentials from requests, but when called at inappropriate times during request processing, it can return cached or default values instead of requiring fresh authentication. The flaw operates at the core of Apache's module system where external modules can interfere with the normal flow of authentication validation, effectively creating a pathway for unauthorized access.
From an operational impact perspective, this vulnerability allows attackers to bypass authentication mechanisms that are supposed to protect sensitive resources, potentially leading to unauthorized access to restricted content, administrative interfaces, or confidential data. The vulnerability is particularly dangerous because it affects third-party modules, meaning that organizations using custom or third-party extensions to Apache HTTP Server are at risk even if they have updated their core server software. Attackers can exploit this by crafting specific requests that trigger the vulnerable module behavior, causing the server to skip proper authentication checks and grant access to protected resources. The impact extends beyond simple credential bypass to potentially enable privilege escalation or full system compromise depending on the protected resources.
Mitigation strategies for CVE-2017-3167 require immediate action including updating Apache HTTP Server to versions 2.2.33 or 2.4.26 and later, which contain the necessary patches to address the improper authentication handling. Organizations should also review and audit third-party modules for proper implementation of authentication functions, ensuring that ap_get_basic_auth_pw() is only called within appropriate authentication phases. Security configurations should be reviewed to minimize the use of vulnerable third-party modules where possible, and network segmentation should be implemented to limit access to sensitive resources. Additionally, monitoring and logging should be enhanced to detect unusual authentication patterns or unauthorized access attempts that might indicate exploitation of this vulnerability. This vulnerability aligns with CWE-284 Access Control Issues and can be mapped to ATT&CK technique T1078 Valid Accounts, as it allows for unauthorized access through bypassed authentication mechanisms.