CVE-2026-93985 in OpenPanel
Summary
by MITRE • 09/19/2026
OpenPanel js-runtime through commit bad75bdd contains a sandbox escape vulnerability in the JavaScript webhook template validator that fails to block computed member access to constructor chains. Attackers with project write access can create webhook templates using computed property notation to access Function constructor and execute arbitrary code in the worker process.
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Analysis
by VulDB Data Team • 09/19/2026
The identified security flaw resides within the OpenPanel js-runtime, specifically affecting the JavaScript webhook template validator component as introduced or modified by commit bad75bdd. This vulnerability represents a critical sandbox escape scenario where the application fails to adequately restrict access to sensitive language constructs during the validation of user-supplied input. The core technical deficiency lies in the handling of computed member access within JavaScript objects. In standard web development practices, developers often use bracket notation for property access when keys are dynamic or contain special characters. However, this implementation incorrectly permits such syntax to traverse prototype chains and reach internal constructors that should remain isolated from user-controlled execution contexts. By allowing computed property notation like obj[constructor] or similar variations, the validator inadvertently exposes the underlying Function constructor, which serves as a powerful mechanism for evaluating arbitrary strings as JavaScript code at runtime.
From an operational perspective, this flaw allows attackers who possess project write access to escalate their privileges significantly beyond what is intended by the application's security model. While standard users might be limited to creating or modifying webhook configurations within predefined boundaries, the ability to inject computed member access enables them to bypass these restrictions entirely. An attacker can craft a malicious webhook template that utilizes this syntax to invoke the Function constructor directly. Once invoked, this allows for the execution of arbitrary commands within the worker process environment where OpenPanel operates. This is particularly dangerous because worker processes often run with elevated privileges relative to standard user accounts and may have access to internal system resources, network interfaces, or other tenant data that should remain strictly isolated. The successful exploitation results in remote code execution on the server hosting the vulnerable instance, potentially leading to full compromise of the underlying infrastructure depending on the configuration and isolation mechanisms employed by the platform.
This vulnerability aligns with CWE-94 Improper Control of Generation of Code (Code Injection) as it involves the injection of executable logic through a template engine that fails to sanitize dynamic code generation paths. Furthermore, in terms of tactical classification under the MITRE ATT&CK framework, this behavior corresponds to T1059 Command and Scripting Interpreter: JavaScript, where attackers leverage scripting languages to execute commands on compromised systems. The specific technique involves abusing language features like computed properties to bypass input validation filters that typically block direct function calls or eval statements. This highlights a common pitfall in web application security where developers focus on blocking explicit keywords while neglecting alternative syntactic structures that achieve the same outcome, such as bracket notation for property access which can resolve to constructor functions if not strictly validated against prototype chains.
Mitigation strategies must address both immediate remediation and long-term architectural improvements. The most effective short-term fix involves updating the OpenPanel js-runtime to a patched version where commit bad75bdd is corrected or superseded by a secure implementation that explicitly blocks computed member access to constructor properties within webhook templates. Developers should implement strict allow-listing for permitted property names rather than relying on blocklists, ensuring that only known safe identifiers are processed during template validation. Additionally, employing Content Security Policy headers and sandbox attributes can provide an additional layer of defense by restricting the execution context of any injected scripts. For organizations currently running vulnerable versions, it is critical to audit webhook configurations for suspicious patterns involving bracket notation or dynamic property access. Regular security assessments focusing on template injection vulnerabilities are also recommended to identify similar weaknesses in other parts of the application that may rely on similar validation logic without adequate safeguards against prototype pollution or constructor abuse.