HtmlUnit prior to 2.37.0 contains code execution vulnerabilities. HtmlUnit initializes Rhino engine improperly, hence a malicious JavScript code can execute arbitrary Java code on the application. Moreover, when embedded in Android application, Android-specific initialization of Rhino engine is done in an improper way, hence a malicious JavaScript code can execute arbitrary Java code on the application.

Certain Neko-related HTML parsers allow a denial of service via crafted Processing Instruction (PI) input that causes excessive heap memory consumption. In particular, this issue exists in HtmlUnit-Neko through 2.26, and is fixed in 2.27. This issue also exists in CyberNeko HTML through 1.9.22 (also affecting OWASP AntiSamy before 1.6.6), but 1.9.22 is the last version of CyberNeko HTML. NOTE: this may be related to CVE-2022-24839.

HtmlUnit NekoHtml Parser before 2.61.0 suffers from a denial of service vulnerability. Crafted input associated with the parsing of Processing Instruction (PI) data leads to heap memory consumption. This is similar to CVE-2022-28366 but affects a much later version of the product.

Those using HtmlUnit to browse untrusted webpages may be vulnerable to Denial of service attacks (DoS). If HtmlUnit is running on user supplied web pages, an attacker may supply content that causes HtmlUnit to crash by a stack overflow. This effect may support a denial of service attack.This issue affects htmlunit before 2.70.0.

HtmlUnit is a GUI-less browser for Java programs. HtmlUnit is vulnerable to Remote Code Execution (RCE) via XSTL, when browsing the attacker’s webpage. This vulnerability has been patched in version 3.9.0