Vulnerability Description
@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.
Related Weaknesses (CWE)
References
- https://github.com/microsoft/kiota-typescript/commit/09f8bd9b34d68bf412a9b78f6ca
- https://github.com/microsoft/kiota-typescript/security/advisories/GHSA-396q-4vc8
- https://github.com/microsoft/kiota-typescript/security/advisories/GHSA-396q-4vc8
FAQ
What is CVE-2026-49336?
CVE-2026-49336 is a documented vulnerability. @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 `Redire...
How severe is CVE-2026-49336?
CVSS scoring is not yet available for CVE-2026-49336. Check NVD for updates.
Is there a patch for CVE-2026-49336?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.