HTTP Stream Wrapper Redirect Handling Heap Buffer Overflow

Executive Summary

This vulnerability occurs in PHP's HTTP stream wrapper when handling redirects. If a server responds to a redirect request with a Location header that has an empty value, the code reads one byte past the end of the buffer storing the location. This out-of-bounds byte determines the redirect target, allowing a malicious server to control whether the client is redirected to the host root or the current directory.

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Detection Guidance

This vulnerability involves HTTP stream wrapper handling of redirects with empty Location headers. Detection requires monitoring HTTP client behavior during redirects. Check PHP error logs for out-of-bounds read warnings and inspect network traffic for malformed redirect responses with empty Location headers. Use tools like tcpdump or Wireshark to capture HTTP responses and verify redirect handling logic in PHP applications.

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Impact Analysis

An attacker could exploit this to manipulate where your application redirects, potentially leading to unauthorized access to sensitive data or unintended actions. For example, it might redirect users to a malicious site or expose internal paths.

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Compliance Impact

This vulnerability could potentially impact compliance with GDPR or HIPAA if it leads to unauthorized data exposure or access. The flaw allows a malicious server to control redirect targets, which might result in unintended data transmission or access to sensitive resources. However, specific compliance impacts depend on how the vulnerability is exploited in a given environment.

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Mitigation Strategies

Update PHP to the latest patched version to address the heap buffer overflow in the HTTP stream wrapper redirect handling. Monitor network traffic for unusual redirect patterns or empty Location headers.

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