Vitest: Windows backslash traversal bypasses the @vitest/mocker redirect allowlist fix

Overview

Vitest is a Vite-native testing framework for JavaScript and TypeScript projects. From 4.1.11 until 4.1.12 and 5.0.3, isFileLoadingAllowed and the filesystem read interpret backslashes differently on Windows in packages/mocker/src/node/interceptorPlugin.ts. When a client can reach the Vite dev server on Windows and register a redirect mock containing backslash traversal, POSIX joining preserves a Windows backslash traversal that the later filesystem read interprets as a path separator, so the client can read a file outside server.fs.allow that the Vitest process can access. This issue is fixed in versions 4.1.12 and 5.0.3.

Affected

• vitest >= 4.1.11, < 4.1.12
• vitest >= 5.0.0-rc.2, < 5.0.3
• mocker >= 4.1.11, < 4.1.12
• mocker >= 5.0.0-rc.2, < 5.0.3

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.