CVE-2019-17240 in Bludit
Summary
by MITRE
bl-kernel/security.class.php in Bludit 3.9.2 allows attackers to bypass a brute-force protection mechanism by using many different forged X-Forwarded-For or Client-IP HTTP headers.
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Analysis
by VulDB Data Team • 08/09/2025
The vulnerability identified as CVE-2019-17240 affects Bludit version 3.9.2 and represents a significant security flaw in the application's brute-force protection mechanism. This issue resides within the security.class.php file of the bl-kernel directory, where the application fails to properly validate or sanitize HTTP headers that are commonly used to determine client IP addresses. The vulnerability specifically impacts the X-Forwarded-For and Client-IP HTTP headers which are typically employed by web applications to identify the original IP address of a client connecting through proxies or load balancers. When these headers are improperly handled, they create an avenue for attackers to circumvent security measures designed to prevent automated login attempts and credential stuffing attacks.
The technical implementation flaw stems from the application's reliance on HTTP headers without proper validation or sanitization of their contents. Attackers can exploit this weakness by sending multiple requests with different forged values in the X-Forwarded-For or Client-IP headers, effectively bypassing the built-in rate-limiting mechanisms that should prevent brute-force attacks. This vulnerability directly maps to CWE-284 Access Control Issues, specifically related to improper access control enforcement when handling user authentication attempts. The flaw demonstrates a classic case of inadequate input validation where the application trusts HTTP headers without verifying their legitimacy or origin, creating a path for attackers to repeatedly attempt login credentials without triggering the intended protection mechanisms.
The operational impact of this vulnerability extends beyond simple credential theft, as it enables attackers to conduct more sophisticated and persistent brute-force attacks against Bludit installations. The bypass of rate-limiting protections means that automated attack tools can continuously attempt to guess login credentials without being blocked by the application's security measures. This creates a significant risk for systems where Bludit is deployed, particularly in environments where the application serves as a content management platform for websites or web applications that may contain sensitive information. The vulnerability is particularly concerning because it affects the core authentication mechanism of the application, potentially allowing unauthorized access to administrative panels and content management features.
Mitigation strategies for CVE-2019-17240 should focus on implementing proper header validation and sanitization within the Bludit application. Organizations should ensure that HTTP headers are properly validated against known legitimate sources or implement additional layers of authentication security such as CAPTCHA mechanisms or multi-factor authentication. The recommended approach includes modifying the security.class.php file to either ignore or properly validate the X-Forwarded-For and Client-IP headers, ensuring that only trusted headers from known proxy servers are accepted. This vulnerability also aligns with ATT&CK technique T1110.003 Credential Stuffing, where attackers leverage bypassed protections to conduct systematic credential guessing attacks. Organizations should consider implementing network-level protections such as IP reputation filtering and rate-limiting at the reverse proxy level to provide additional defense-in-depth measures against this specific attack vector. The fix should also include proper logging and monitoring of authentication attempts to detect potential abuse of the bypassed security mechanisms.