Medium, CVSS 5.5npmAmendedPublished
@microsoft/kiota-http-fetchlibrary: Bearer token and Cookie leak across origin on redirect due to case-mismatched scrub in fetchRequestAdapter
CVE-2026-49336 · GHSA-396q-4vc8-28x9
- Affected
- npm @microsoft/kiota-http-fetchlibrary >= 1.0.0-preview.97, <= 1.0.0-preview.101
- Fixed in
- 1.0.0-preview.102· Vendor fix available
- Issue
- @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. Affected versions @microsoft/kiota-http-fetchlibrary = 1.0.0-preview.97…
Recommended action: Upgrade to 1.0.0-preview.102 (pre-release) or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.