CVE-2019-20006 in ezXML
Summary
by MITRE
An issue was discovered in ezXML 0.8.3 through 0.8.6. The function ezxml_char_content puts a pointer to the internal address of a larger block as xml->txt. This is later deallocated (using free), leading to a segmentation fault.
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Analysis
by VulDB Data Team • 03/17/2024
The vulnerability identified as CVE-2019-20006 resides within the ezXML library version 0.8.3 through 0.8.6, representing a critical memory management flaw that can lead to system instability and potential exploitation. This issue manifests in the ezxml_char_content function where the library improperly handles memory pointers, creating a scenario that can result in segmentation faults during program execution. The flaw stems from the library's improper handling of internal memory blocks and their subsequent deallocation processes.
The technical root cause of this vulnerability involves the ezxml_char_content function storing a pointer to an internal memory block's address within the xml->txt field. This pointer references a larger memory block that is subsequently deallocated using the standard free() function. When the program attempts to access or manipulate this freed memory location, it triggers a segmentation fault due to accessing invalid memory addresses. This memory management error constitutes a classic use-after-free vulnerability pattern that falls under CWE-416, specifically related to the use of freed memory.
From an operational perspective, this vulnerability presents significant risks to applications that rely on ezXML for XML processing tasks. The segmentation fault can cause application crashes, leading to denial of service conditions that may be exploited by malicious actors to disrupt services or potentially escalate privileges. The vulnerability is particularly concerning in server applications or systems where XML parsing is frequent, as the crash can be triggered through malformed XML input, creating a potential vector for remote code execution or service disruption. The flaw affects the library's ability to properly manage memory resources, potentially allowing attackers to manipulate memory contents or cause unpredictable program behavior.
The impact extends beyond simple application crashes, as this vulnerability can be leveraged in broader attack scenarios within the MITRE ATT&CK framework, specifically under the T1499 category of Network Denial of Service. Security professionals must consider the potential for this vulnerability to be combined with other exploits or used as a stepping stone for more sophisticated attacks. The vulnerability's presence in widely-used XML parsing libraries means that numerous applications across different platforms and technologies may be affected, amplifying the potential impact. Organizations should prioritize patching or updating their ezXML library versions to address this memory management issue.
Mitigation strategies should focus on immediate library updates to versions that have resolved this memory handling flaw, as well as implementing proper input validation and sanitization for XML data to prevent exploitation attempts. Additionally, application-level protections such as memory protection mechanisms and runtime monitoring can help detect and prevent exploitation attempts. The vulnerability highlights the importance of proper memory management practices in C-based libraries and underscores the need for thorough testing of memory allocation and deallocation patterns to prevent such critical flaws from persisting in production environments.