CVE-2007-1862 in HTTP Server
Summary
by MITRE
The recall_headers function in mod_mem_cache in Apache 2.2.4 does not properly copy all levels of header data, which can cause Apache to return HTTP headers containing previously used data, which could be used by remote attackers to obtain potentially sensitive information.
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Analysis
by VulDB Data Team • 06/09/2025
The vulnerability identified as CVE-2007-1862 resides within the mod_mem_cache module of Apache HTTP Server version 2.2.4, representing a critical information disclosure flaw that exploits improper memory management during HTTP header processing. This vulnerability specifically affects the recall_headers function which is responsible for retrieving and returning HTTP headers to clients. The flaw manifests when the module fails to adequately copy all levels of header data from memory, creating a scenario where stale or previously used header information persists in memory and gets inadvertently returned to clients. The root cause of this issue stems from inadequate memory copying operations within the caching mechanism, where header data structures are not properly sanitized or overwritten between different request cycles, leading to potential data leakage.
The technical implementation of this vulnerability operates through the Apache module system's memory management practices during concurrent request processing. When multiple HTTP requests are handled sequentially, the mod_mem_cache module maintains header information in memory for performance optimization purposes. However, the recall_headers function does not perform complete memory copying operations, leaving portions of previously processed header data in memory locations that are subsequently reused for new requests. This creates a situation where header fields from one request may contain remnants from previous requests, potentially exposing sensitive information such as authentication tokens, session identifiers, or other confidential data that should not be accessible to unauthorized parties. The vulnerability is particularly concerning because it operates at the HTTP protocol level, affecting the fundamental communication between web server and client.
The operational impact of CVE-2007-1862 extends beyond simple information disclosure, as it represents a significant security risk that could enable sophisticated attacks targeting sensitive web applications. Attackers could leverage this vulnerability to harvest session cookies, authentication credentials, or other confidential header data that might be cached in memory during previous requests. This information could then be used to impersonate legitimate users, gain unauthorized access to protected resources, or conduct further reconnaissance activities. The vulnerability is particularly dangerous in environments where Apache serves applications with sensitive data, such as financial services, healthcare portals, or government systems where header data might contain personally identifiable information or other classified content. According to CWE classification, this vulnerability maps to CWE-200 Information Exposure, specifically related to improper handling of cached data in memory structures. The attack vector aligns with ATT&CK technique T1552.001 Unsecured Credentials, as the vulnerability enables attackers to access cached authentication information through HTTP headers.
Mitigation strategies for CVE-2007-1862 require immediate attention and systematic implementation across affected Apache installations. The most effective immediate solution involves upgrading to Apache HTTP Server version 2.2.5 or later, where the memory copying operations within mod_mem_cache have been corrected to ensure complete header data sanitization. Organizations should also implement proper configuration management to disable mod_mem_cache when it is not required, particularly in environments where security is paramount. Additional protective measures include implementing strict header sanitization policies, monitoring for unusual header patterns in server logs, and conducting regular security audits of caching mechanisms. Network segmentation and access controls should be strengthened to limit exposure, while security teams should establish monitoring procedures to detect potential exploitation attempts. The vulnerability demonstrates the critical importance of proper memory management in web server modules and highlights the need for comprehensive security testing of caching mechanisms. Organizations should also consider implementing automated patch management systems to ensure timely deployment of security updates. This vulnerability serves as a reminder that even seemingly minor memory handling flaws in web server components can result in significant security implications, particularly when dealing with sensitive header data that is frequently cached and reused across multiple requests.