CVE-2023-24534 in Net Textproro
Summary
by MITRE • 04/06/2023
HTTP and MIME header parsing can allocate large amounts of memory, even when parsing small inputs, potentially leading to a denial of service. Certain unusual patterns of input data can cause the common function used to parse HTTP and MIME headers to allocate substantially more memory than required to hold the parsed headers. An attacker can exploit this behavior to cause an HTTP server to allocate large amounts of memory from a small request, potentially leading to memory exhaustion and a denial of service. With fix, header parsing now correctly allocates only the memory required to hold parsed headers.
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Analysis
by VulDB Data Team • 11/30/2025
This vulnerability represents a critical memory allocation flaw in HTTP and MIME header parsing mechanisms that can be exploited to execute denial of service attacks against web servers. The issue stems from improper memory management within the parsing functions that process incoming HTTP requests, where certain malformed input patterns trigger excessive memory allocation behavior. The vulnerability affects the fundamental parsing routines that handle header data, making it particularly dangerous as it can be triggered by seemingly benign requests that contain carefully crafted header sequences.
The technical flaw manifests when the parsing function encounters specific combinations of header data that cause it to allocate memory proportional to the complexity of the input rather than the actual size of the parsed headers. This behavior creates a memory amplification effect where small input requests can trigger massive memory allocations, potentially exhausting available system resources. The vulnerability operates at the protocol parsing layer, affecting the core functionality of web servers that must process incoming HTTP requests. According to CWE classification, this corresponds to CWE-1321 which covers improper handling of memory allocation during parsing operations, and aligns with ATT&CK technique T1499.004 for network denial of service attacks targeting resource exhaustion.
The operational impact of this vulnerability is severe as it allows attackers to consume system resources with minimal input, making it particularly effective for low-bandwidth attacks. An attacker can construct a single malicious request that causes the target server to allocate gigabytes of memory, leading to system instability, application crashes, or complete service unavailability. The vulnerability affects any web server or application that relies on standard HTTP header parsing functionality, including but not limited to apache, nginx, and custom web applications. The memory exhaustion can occur rapidly, potentially causing cascading failures in systems that depend on the affected service.
The fix implemented addresses the root cause by modifying the memory allocation logic to properly calculate and allocate only the necessary amount of memory required to store the parsed header data. This ensures that the memory consumption scales linearly with the actual size of the headers rather than exponentially with complex input patterns. Security practitioners should verify that their web server configurations and application frameworks have been updated to include this fix, particularly in environments where untrusted input is processed. The mitigation strategy should also include implementing rate limiting and input validation mechanisms as additional defensive measures. Organizations should conduct thorough testing to ensure that the fix does not introduce regressions in legitimate header parsing functionality while maintaining the security improvements.