CVE-2023-38709 in HTTP Server
Summary
by MITRE • 04/04/2024
Faulty input validation in the core of Apache allows malicious or exploitable backend/content generators to split HTTP responses.
This issue affects Apache HTTP Server: through 2.4.58.
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Analysis
by VulDB Data Team • 05/05/2026
The vulnerability identified as CVE-2023-38709 represents a critical flaw in the Apache HTTP Server core that stems from inadequate input validation mechanisms. This weakness specifically impacts versions through 2.4.58 and creates a pathway for malicious actors to manipulate HTTP response handling within the server infrastructure. The vulnerability manifests when backend or content generators fail to properly validate input parameters, leading to potential response splitting attacks that can compromise the integrity of web communications. The flaw exists at the fundamental level of how Apache processes and validates incoming requests before generating appropriate responses, creating an attack surface that extends beyond typical web application boundaries.
The technical implementation of this vulnerability allows attackers to inject malicious content into HTTP responses through carefully crafted input sequences that bypass standard validation checks. When Apache processes requests containing specially formatted data, the insufficient input sanitization permits attackers to manipulate response headers and content in ways that can lead to various security consequences including cache poisoning, session hijacking, and cross-site scripting attacks. This vulnerability operates at the protocol level rather than application level, making it particularly dangerous as it can affect all applications running on the affected Apache server instance. The flaw essentially creates a condition where response splitting occurs when the server fails to properly sanitize input before incorporating it into HTTP response generation, which is a fundamental security failure in the request processing pipeline.
The operational impact of CVE-2023-38709 extends far beyond simple data corruption or service disruption. Organizations running affected Apache versions face significant risks including potential data breaches, unauthorized access to sensitive information, and complete compromise of web application security. Attackers can exploit this vulnerability to inject malicious content into responses, potentially redirecting users to phishing sites or executing malicious scripts in the context of legitimate web applications. The vulnerability aligns with CWE-129, which addresses improper validation of input boundaries, and can be mapped to ATT&CK technique T1190 for exploiting vulnerabilities in web applications. This flaw particularly affects web applications that rely on dynamic content generation, proxy configurations, and any system where Apache acts as an intermediary between clients and backend services.
Mitigation strategies for CVE-2023-38709 must include immediate deployment of Apache HTTP Server updates to versions that address the input validation issues. Organizations should implement comprehensive input filtering and sanitization measures at all levels of their web infrastructure, including proxy servers and application layers. Network administrators should consider implementing additional security controls such as web application firewalls and response header validation to detect and prevent exploitation attempts. The vulnerability demonstrates the importance of proper input validation and the principle of least privilege in web server configurations, as outlined in OWASP Top Ten security practices. Organizations should also conduct thorough security assessments of their Apache installations to identify any other potential vulnerabilities in their web infrastructure and implement monitoring solutions that can detect anomalous response patterns indicative of exploitation attempts.