CVE-2021-20086: 
JavaScript vulnerability analysis and mitigation

CVE-2021-20086 is a prototype pollution vulnerability discovered in jquery-bbq version 1.2.1. The vulnerability allows malicious users to inject properties into Object.prototype through improperly controlled modification of object prototype attributes (CVE Mitre, NVD).

The vulnerability exists in the $.deparam function of jquery-bbq, which is responsible for URL parameter parsing. The function does not properly sanitize input when processing URL parameters, allowing an attacker to manipulate the object prototype through specially crafted URL parameters. The vulnerability can be exploited using parameters like '?proto[test]=test' or '?constructor[prototype][test]=test' (GitHub PoC).

When successfully exploited, this vulnerability allows attackers to inject arbitrary properties into the JavaScript Object.prototype, which can affect all objects in the application. This could potentially lead to application behavior manipulation and security bypass scenarios (NVD).

Users should upgrade to a patched version of jquery-bbq if available, or implement input validation to prevent prototype pollution attempts. If neither option is feasible, carefully reviewing and sanitizing URL parameters before processing them through the $.deparam function is recommended (NVD).