@microsoft/kiota-http-fetchlibrary provides TypeScript libraries for Kiota-generated API clients. In versions 1.0.0-preview.97 through 1.0.0-preview.101, "@microsoft/kiota-http-fetchlibrary"'s "RedirectHandler" is documented as stripping "Authorization" and "Cookie" from cross-origin redirect targets, but the default "scrubSensitiveHeaders" callback in "RedirectHandlerOptions" uses case-sensitive property deletion ("delete headers.Authorization", "delete headers.Cookie") on a headers object that "FetchRequestAdapter.getRequestFromRequestInformation" has already lower-cased. The delete therefore targets keys that do not exist, the scrub is a no-op, and any Bearer token or Cookie attached by a kiota-generated SDK is forwarded to an attacker-controlled host across a 30x redirect. This is reachable in the default middleware chain ("MiddlewareFactory.getDefaultMiddlewares") with no custom configuration, and applies to every kiota-generated TypeScript SDK that uses "BaseBearerTokenAuthenticationProvider" or any other authentication provider that sets the "Authorization" request header. Version 1.0.0-preview.102 patches the issue.