A Vertex job id is a base64url-encoded operation name, and base64url decoding
accepts arbitrary bytes without throwing, so the previous decode-and-split
check let a crafted id splice a path traversal into the fetch URL while the
Bearer token stayed attached — e.g. "..%2F..%2Fevil" resolved to
/v1/evil:fetchPredictOperation on the Vertex host. body.model had the same
shape on the create path, where it is interpolated into the URL unescaped.
decodeJobId now requires a charset-only id, a byte-for-byte round-trip, and a
decoded name matching ^projects/{p}/locations/{l}/publishers/{pub}/models/{m}/operations/{op}$
— no field may contain "/", so ".." can never reach the URL. model ids are
restricted to [A-Za-z0-9._-].
Co-Authored-By: Claude Code <noreply@anthropic.com>
da6aa90128