CVE-2021-41248 in IDE
Summary
by MITRE • 11/05/2021
GraphiQL is the reference implementation of this monorepo, GraphQL IDE, an official project under the GraphQL Foundation. All versions of graphiql older than [email protected] are vulnerable to compromised HTTP schema introspection responses or schema prop values with malicious GraphQL type names, exposing a dynamic XSS attack surface that can allow code injection on operation autocomplete. In order for the attack to take place, the user must load a vulnerable schema in graphiql. There are a number of ways that can occur. By default, the schema URL is not attacker-controllable in graphiql or in its suggested implementations or examples, leaving only very complex attack vectors. If a custom implementation of graphiql's fetcher allows the schema URL to be set dynamically, such as a URL query parameter like ?endpoint= in graphql-playground, or a database provided value, then this custom graphiql implementation is vulnerable to phishing attacks, and thus much more readily available, low or no privelege level xss attacks. The URLs could look like any generic looking graphql schema URL. It should be noted that desktop clients such as Altair, Insomnia, Postwoman, do not appear to be impacted by this. This vulnerability does not impact codemirror-graphql, monaco-graphql or other dependents, as it exists in onHasCompletion.ts in graphiql. It does impact all forks of graphiql, and every released version of graphiql.
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Analysis
by VulDB Data Team • 11/09/2021
The vulnerability identified as CVE-2021-41248 affects GraphiQL, which serves as the reference implementation of the GraphQL IDE and operates as an official project under the GraphQL Foundation. This security flaw exists within the dynamic schema introspection functionality of GraphiQL versions prior to [email protected], creating a significant cross-site scripting (XSS) attack surface that can enable code injection during operation autocomplete. The vulnerability stems from the improper handling of GraphQL type names in schema introspection responses or schema prop values, allowing malicious actors to inject harmful code through the autocomplete feature.
The technical exploitation of this vulnerability requires a user to load a vulnerable schema into GraphiQL, which can occur through multiple vectors including custom implementations that permit dynamic schema URL configuration. While default GraphiQL implementations maintain non-attacker-controllable schema URLs, custom deployments that accept dynamic schema sources through query parameters or database values create readily exploitable attack paths. These attack vectors can involve phishing techniques where malicious schema URLs appear legitimate, making them particularly dangerous as they require minimal privilege levels to execute. The vulnerability specifically resides in the onHasCompletion.ts file within the GraphiQL codebase, making it distinct from other GraphQL-related components such as codemirror-graphql or monaco-graphql that remain unaffected by this particular flaw.
The operational impact of this vulnerability extends across all forks and released versions of GraphiQL, creating widespread exposure throughout the GraphQL ecosystem. Desktop GraphQL clients including Altair, Insomnia, and Postwoman are unaffected by this specific vulnerability, indicating the scope is limited to web-based implementations. The attack surface becomes significantly more accessible when custom GraphiQL implementations allow dynamic schema URL setting, potentially enabling low-effort XSS attacks that could compromise user sessions or execute unauthorized operations against GraphQL endpoints. This vulnerability aligns with CWE-79 (Cross-site Scripting) and follows ATT&CK techniques related to code injection and credential theft through web application vulnerabilities. The exploitation pattern demonstrates how seemingly benign schema introspection functionality can become a critical security weakness when proper input sanitization and output encoding are not implemented, particularly in development tools that are frequently used in sensitive environments where GraphQL APIs are exposed to various user interactions.