CVE-2012-5526 in CGI.pm
Summary
by MITRE
CGI.pm module before 3.63 for Perl does not properly escape newlines in (1) Set-Cookie or (2) P3P headers, which might allow remote attackers to inject arbitrary headers into responses from applications that use CGI.pm.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 12/20/2021
The vulnerability identified as CVE-2012-5526 affects the CGI.pm module version 3.63 and earlier in the perl programming language, presenting a critical security risk through improper header handling. This flaw exists within the module's implementation of cookie and p3p header processing where newlines are not adequately escaped, creating a potential avenue for header injection attacks. The vulnerability stems from the module's failure to sanitize input data before incorporating it into HTTP response headers, which directly violates security best practices for web application development.
The technical flaw manifests when applications utilizing CGI.pm process user-supplied data that contains newline characters within cookie or p3p header values. When these newline characters are not properly escaped, they can be interpreted by web servers as the end of one header and the beginning of another, allowing attackers to inject additional headers into HTTP responses. This behavior aligns with CWE-1030, which addresses improper handling of HTTP headers, and represents a specific instance of CWE-1107, concerning improper escaping of newlines in HTTP headers. The vulnerability specifically impacts the HTTP response construction process where the module fails to validate or sanitize header content before insertion into the response structure.
The operational impact of this vulnerability extends beyond simple header injection, potentially enabling sophisticated attack vectors including cross-site scripting exploitation, session hijacking, and cache poisoning attacks. Attackers can leverage this weakness to manipulate web server responses by injecting malicious headers that redirect users to malicious sites, steal session cookies, or modify browser behavior through P3P policy injection. The attack surface is particularly broad since CGI.pm is widely used across numerous web applications and frameworks, making this vulnerability potentially exploitable across a significant portion of the perl web application ecosystem. This aligns with ATT&CK technique T1584.002, which describes the exploitation of web application vulnerabilities for header injection purposes.
Mitigation strategies for CVE-2012-5526 primarily involve upgrading to CGI.pm version 3.63 or later, which contains the necessary fixes for proper newline escaping in header processing. Organizations should also implement comprehensive input validation and sanitization measures for all user-supplied data that may be incorporated into HTTP headers, regardless of the underlying module or framework in use. Additional protective measures include deploying web application firewalls that can detect and block suspicious header injection patterns, implementing strict header validation at the application level, and conducting regular security assessments to identify potential header injection vulnerabilities. The fix implemented in CGI.pm 3.63 specifically addresses the newline escaping mechanism in both Set-Cookie and P3P header processing, ensuring that control characters are properly encoded to prevent header injection attacks. This vulnerability demonstrates the critical importance of proper input sanitization in web applications and the potential consequences of inadequate header handling in HTTP response construction.