A major safety flaw has been found in Completely happy DOM, a preferred JavaScript DOM implementation, affecting variations as much as v19.
This vulnerability locations programs vulnerable to Distant Code Execution (RCE) assaults, probably impacting the package deal’s 2.7 million weekly customers.
The flaw arises as a result of the Node.js VM Context utilized by Completely happy DOM is just not a totally remoted atmosphere, which might permit untrusted code to flee and acquire entry to the underlying system’s functionalities.
The first situation is that Completely happy DOM has JavaScript analysis enabled by default, a element that might not be obvious to all builders utilizing the library.
This default configuration turns into a safety danger when the atmosphere executes untrusted code. An attacker can craft malicious JavaScript that traverses the constructor chain to entry the process-level Perform constructor.
This permits them to execute code exterior the supposed sandboxed atmosphere, resulting in a full VM escape.
The kind of module system in use CommonJS or ESM determines the extent of the attacker’s management. In a CommonJS atmosphere, an attacker can entry the require() perform, which permits them to load Node.js modules and carry out unauthorized actions.
Potential Assault Situations
The implications of this vulnerability are far-reaching, particularly for functions that use Server-Aspect Rendering (SSR) or testing frameworks that course of exterior content material.
An attacker may inject a malicious script into user-controlled HTML, which might then be executed on the server. Profitable exploitation may result in a number of damaging outcomes:
Knowledge Exfiltration: Getting access to delicate info like atmosphere variables, configuration recordsdata, and different secrets and techniques.
Lateral Motion: Utilizing community entry to hook up with different inside programs. Though Completely happy DOM has some community protections, a compromised course of may bypass them.
Code Execution: Acquiring baby course of entry to run arbitrary instructions on the server.
Persistence: Modifying the file system to keep up a long-term presence on the compromised system.
Mitigations
The builders of Completely happy DOM have launched a patched model to deal with this vulnerability. Customers are strongly suggested to take rapid motion to guard their programs.
The really useful plan of action is to replace to Completely happy DOM v20 or newer. This up to date model disables JavaScript analysis by default and features a warning whether it is enabled in what is taken into account an insecure atmosphere.
For customers who require JavaScript analysis, it’s essential to run Node.js with the –disallow-code-generation-from-strings flag.
This setting prevents the usage of eval() and Perform() on the course of stage, closing the loophole that permits for the VM escape.
If a right away replace is just not possible, builders ought to disable JavaScript analysis manually except the content material being processed is from a totally trusted supply.
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