CVE-2019-20005 in ezXML
Summary
by MITRE
An issue was discovered in ezXML 0.8.3 through 0.8.6. The function ezxml_decode, while parsing a crafted XML file, performs incorrect memory handling, leading to a heap-based buffer over-read while running strchr() starting with a pointer after a '\0' character (where the processing of a string was finished).
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Analysis
by VulDB Data Team • 03/17/2024
The vulnerability identified as CVE-2019-20005 represents a critical heap-based buffer over-read flaw within the ezXML library version 0.8.3 through 0.8.6. This issue manifests during the processing of malformed XML content when the ezxml_decode function attempts to parse crafted input files. The flaw stems from improper memory handling practices that allow the function to access memory locations beyond the intended buffer boundaries. The vulnerability specifically occurs when the strchr() function is invoked with a pointer that has already advanced past the null terminator character of a processed string, creating an exploitable condition where arbitrary memory contents may be read beyond the allocated buffer limits.
The technical exploitation of this vulnerability involves the manipulation of XML parsing routines within the ezXML library, which is commonly used for XML document processing in various applications and systems. When the library encounters specially crafted XML input, the ezxml_decode function fails to properly validate string boundaries before invoking strchr(), resulting in memory access violations that can lead to information disclosure, application crashes, or potentially more severe consequences depending on the execution context. This memory handling error creates a condition where the parsing logic continues to traverse memory beyond the intended string boundaries, potentially exposing sensitive data from adjacent memory regions or causing unpredictable application behavior.
From an operational perspective, this vulnerability poses significant risks to systems that rely on ezXML for XML processing, particularly those handling untrusted input from external sources. The impact extends across multiple security domains as it can be leveraged to extract sensitive information from memory, potentially including authentication tokens, cryptographic keys, or other confidential data residing in adjacent memory locations. The vulnerability's classification aligns with CWE-125, which addresses out-of-bounds read conditions, and represents a classic example of improper input validation leading to memory safety issues. The flaw demonstrates how seemingly benign XML parsing operations can become security threats when proper boundary checking mechanisms are absent or inadequate.
The mitigation strategies for CVE-2019-20005 primarily focus on upgrading to a patched version of the ezXML library, specifically versions beyond 0.8.6 where the memory handling issues have been resolved. System administrators should also implement input validation measures to filter and sanitize XML content before processing, particularly when dealing with external or untrusted sources. Additional protective measures include deploying memory corruption detection tools, implementing application sandboxing, and ensuring that affected applications are regularly updated with security patches. Organizations should also consider implementing network segmentation and monitoring to detect potential exploitation attempts, as the vulnerability can be triggered through XML injection attacks. The ATT&CK framework categorizes this issue under privilege escalation and information gathering techniques, as successful exploitation could lead to unauthorized access to sensitive system information and potentially provide attackers with footholds for further compromise of affected systems.