CVE-2026-96759 in orval
Summary
by MITRE • 09/23/2026
orval before 8.29.0 fails to escape the operationId parameter when emitting it into generated TanStack Query mutator options metadata objects. Attackers can inject arbitrary JavaScript code through a crafted operationId in an OpenAPI specification that executes when generated hooks are called.
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Analysis
by VulDB Data Team • 09/23/2026
The vulnerability identified in Orval versions prior to 8.29.0 represents a significant security flaw within the code generation pipeline, specifically affecting how metadata is constructed for TanStack Query mutator options. As a widely used tool for generating TypeScript clients from OpenAPI specifications, Orval processes various parameters defined in API schemas to produce functional client-side hooks and utilities. The core issue lies in the handling of the operationId field, which serves as a unique identifier for each endpoint within an OpenAPI document. When Orval generates code that integrates with TanStack Query, it embeds metadata objects into the resulting JavaScript or TypeScript files. In vulnerable versions, this process fails to properly sanitize or escape special characters present in the user-defined operationId string before embedding it directly into these metadata structures.
This lack of input validation allows for a classic injection vulnerability where an attacker can manipulate the generated code structure by supplying a maliciously crafted operationId within the source OpenAPI specification file. Because the operationId is often used as part of keys or identifiers in JavaScript objects, injecting specific characters such as quotes, semicolons, or curly braces can alter the syntax and logic of the generated client code. When this flawed code is executed by an application consuming the Orval-generated library, particularly when invoking hooks that rely on these metadata structures, the injected payload executes within the context of the user's browser environment. This constitutes a Stored Cross-Site Scripting (XSS) vector if the OpenAPI specification itself is considered trusted input from a malicious source or compromised API definition repository.
The operational impact of this vulnerability extends beyond simple code generation errors; it introduces a persistent risk to applications that consume the generated client libraries. If an organization integrates an Orval-generated library derived from a tainted OpenAPI spec, every instance where the affected hooks are called can trigger arbitrary JavaScript execution in the end-user's browser. This capability enables attackers to perform session hijacking by stealing authentication cookies or tokens, deface web pages, redirect users to phishing sites, or execute further attacks within the trusted context of the application domain. The severity is compounded by the fact that code generation tools are often perceived as safe infrastructure components, leading developers to overlook security reviews on the generated output files themselves.
From a classification perspective, this vulnerability aligns with CWE-79 Improper Neutralization of Input During Web Page Generation commonly known as Cross-site Scripting. The specific mechanism involves improper handling of user-controllable input during the construction of web content or script objects. In terms of offensive security frameworks, this maps to ATT&CK technique T1059 Command and Scripting Interpreter, specifically JavaScript execution via client-side injection. It also relates to CWE-20 Improper Input Validation as the root cause is the failure to validate and sanitize input data before processing it into executable code structures.
Mitigation strategies must focus on both immediate remediation and long-term defensive coding practices. The primary solution is to upgrade Orval to version 8.29.0 or later, where this specific escaping logic for operationId has been corrected to ensure that special characters are properly encoded before being embedded in metadata objects. For organizations unable to immediately update their dependencies, implementing a pre-commit hook or CI/CD pipeline check to scan OpenAPI specifications for suspicious patterns in the operationId field can provide temporary protection. Additionally, developers should adopt strict Content Security Policy (CSP) headers within their web applications to restrict inline script execution and mitigate the impact of any successful injection attempts. Regular auditing of third-party code generation tools and their outputs is essential to maintain a secure software supply chain.