GHSA-hqj5-cw9f-rx67

Summary

swagger-typescript-api interpolates servers[0].url directly into a TypeScript class-body field initializer of the generated fetch HttpClient (templates/base/http-clients/fetch-http-client.ejs:75), without any escaping. A malicious URL containing a " closes the string literal that initializes public baseUrl and exposes the surrounding class body to injection. The most direct exploit declares a new static field whose initializer is an async IIFE — TypeScript evaluates static field initializers at class definition time, which is at module load. A consumer who imports the generated client (or anything that transitively imports it) executes the injected code with no further interaction — no instantiation, no method call, no use of the baseUrl. The attacker controls the OpenAPI spec; the victim is whoever runs the generator and imports the result.

This is the highest-impact sink in the package: the trigger requires only a bare import of the generated module.

Details

createApiConfig in src/code-gen-process.ts:591 sets the templated baseUrl from the spec without sanitization:

return {
  ...
  baseUrl: serverUrl,     // <-- serverUrl = swaggerSchema.servers[0].url, raw
  ...
};

The fetch http-client template (templates/base/http-clients/fetch-http-client.ejs:75) then interpolates that value into a TS string literal that initializes a public class-body field of the generated HttpClient:

export class HttpClient<SecurityDataType = unknown> {
    public baseUrl: string = "<%~ apiConfig.baseUrl %>";
    private securityData: SecurityDataType | null = null;
    ...
}

<%~ %> is Eta's raw, unescaped interpolation. The codebase's only escape function — escapeJSDocContent (src/schema-parser/schema-formatters.ts:127) — only replaces */ and is not applied to this path.

TypeScript class-body grammar permits any number of field declarations and static blocks between { and }. A spec value of...