CVE-2022-23943 in HTTP Server
Summary
by MITRE • 03/14/2022
Out-of-bounds Write vulnerability in mod_sed of Apache HTTP Server allows an attacker to overwrite heap memory with possibly attacker provided data. This issue affects Apache HTTP Server 2.4 version 2.4.52 and prior versions.
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Analysis
by VulDB Data Team • 08/11/2025
The CVE-2022-23943 vulnerability represents a critical out-of-bounds write flaw within the mod_sed module of the Apache HTTP Server software ecosystem. This vulnerability specifically targets the sed module which provides stream editing capabilities for server-side processing of web content. The flaw exists in Apache HTTP Server versions 2.4.52 and earlier, making a significant portion of deployed server configurations susceptible to exploitation. The vulnerability is particularly concerning as it allows for heap memory corruption, a class of issues that can lead to arbitrary code execution or complete system compromise when properly exploited.
The technical nature of this vulnerability stems from improper bounds checking within the mod_sed module's handling of input data. When processing certain stream editing operations, the module fails to validate the boundaries of memory allocations, allowing an attacker to write data beyond the allocated heap memory regions. This out-of-bounds write condition occurs during the processing of sed commands that manipulate text streams, where attacker-controlled input can influence the memory layout and overwrite adjacent memory segments. The vulnerability is classified under CWE-787, which specifically addresses out-of-bounds write conditions in software systems, and aligns with ATT&CK technique T1059.007 for command and scripting interpreter usage in exploitation contexts.
The operational impact of CVE-2022-23943 extends beyond simple memory corruption, as it can potentially enable remote code execution when exploited by malicious actors. An attacker who can control the input to the sed module can manipulate memory contents to redirect program execution flow, potentially leading to complete system compromise. The vulnerability's exploitation requires a specific configuration where the mod_sed module is enabled and accessible through web requests, making it particularly dangerous in environments where server-side text processing is utilized. This issue affects not only the stability of the Apache server but also poses significant risks to the broader network infrastructure, as compromised servers can serve as launching points for further attacks.
Mitigation strategies for this vulnerability involve immediate patching of affected Apache HTTP Server installations to version 2.4.53 or later, which contains the necessary fixes for the out-of-bounds write condition. Organizations should also consider disabling the mod_sed module if it is not actively required for their web server operations, as this provides an additional layer of defense against exploitation attempts. Network segmentation and monitoring of web server traffic can help detect potential exploitation attempts, while regular security audits should verify that all Apache installations are running patched versions. The vulnerability demonstrates the importance of proper input validation and memory safety practices in server-side applications, aligning with security best practices outlined in NIST SP 800-53 and ISO 27001 frameworks for protecting against memory corruption vulnerabilities.