CVE-2019-16164 in MyHTML
Summary
by MITRE
MyHTML through 4.0.5 has a NULL pointer dereference in myhtml_tree_node_remove in tree.c.
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Analysis
by VulDB Data Team • 12/18/2023
CVE-2019-16164 represents a critical null pointer dereference vulnerability within the MyHTML library version 4.0.5 and earlier. This vulnerability exists in the tree.c source file at the myhtml_tree_node_remove function, which is responsible for managing the removal of nodes from the HTML document tree structure. The flaw occurs when the function attempts to dereference a pointer that may be null, leading to a potential application crash or system instability. This type of vulnerability falls under the category of improper handling of null values, which is commonly classified as CWE-476. The vulnerability is particularly concerning because it can be exploited through malformed HTML input that triggers the node removal process, potentially allowing attackers to cause denial of service conditions in applications that rely on MyHTML for HTML parsing.
The operational impact of this vulnerability extends beyond simple application crashes, as it can be leveraged in broader attack scenarios within software systems that process untrusted HTML content. When an application using MyHTML encounters malformed HTML that triggers the vulnerable code path, the null pointer dereference can result in abrupt termination of the process, creating opportunities for denial of service attacks. This vulnerability is especially dangerous in web applications, content management systems, or any software that parses HTML from user inputs or external sources. The attack surface is significant given that MyHTML is used in various applications requiring HTML parsing capabilities, making this vulnerability potentially exploitable across multiple platforms and systems that integrate this library.
Mitigation strategies for CVE-2019-16164 should prioritize immediate patching of the MyHTML library to version 4.0.6 or later, where the null pointer dereference has been addressed through proper null checking before pointer dereference operations. Organizations should implement input validation and sanitization measures to prevent malformed HTML from reaching the vulnerable parsing functions, particularly in applications processing user-generated content. Additionally, deployment of application-level protections such as sandboxing, memory protection mechanisms, and proper error handling can help contain the impact of potential exploitation attempts. From a defensive perspective, this vulnerability aligns with ATT&CK technique T1499.004, which covers the use of resource exhaustion to cause denial of service, and represents a classic example of how improper error handling can create exploitable conditions in parsing libraries. The vulnerability demonstrates the importance of robust null pointer validation in memory management operations and highlights the necessity of thorough code review processes for parsing libraries that handle untrusted input data.