Prototype Pollution

Vulnerability

Overview CVE-2020-7702 affects all versions of the templ8 npm package. The vulnerability is a Prototype Pollution issue in the parse function, which allows an attacker to inject arbitrary properties into the global Object prototype [1]. This can be triggered by passing a crafted input that includes properties like __proto__ or constructor.prototype.

Exploitation

Mechanism Prototype Pollution occurs when a JavaScript library unsafely merges objects or defines properties by path [2]. In templ8, the parse function does not properly sanitize input, allowing an attacker to overwrite properties on Object.prototype. For example, an attacker could send a request with a payload containing __proto__.polluted set to a malicious value, which then propagates to all objects in the application [2].

Impact

Successful exploitation can lead to denial of service through JavaScript exceptions or, in some cases, remote code execution [2]. By polluting fundamental object properties, an attacker can alter the application's behavior, potentially leading to arbitrary code execution if the polluted properties are used in security-sensitive contexts.

Mitigation

Status As of the publication date, no fix has been released for templ8. Users should consider replacing the package with a maintained alternative or implementing input validation to prevent prototype pollution attacks [1]. The package may be deprecated or unmaintained.