CVE-2026-49336
@microsoft/kiota-http-fetchlibrary: Bearer token and Cookie leak across origin on redirect due to case-mismatched scrub in fetchRequestAdapter
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.
INFO
Published Date :
June 19, 2026, 6:19 p.m.
Last Modified :
June 19, 2026, 6:19 p.m.
Remotely Exploit :
No
Source :
GitHub_M
Affected Products
The following products are affected by CVE-2026-49336
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
Solution
- Update @microsoft/kiota-http-fetchlibrary to version 1.0.0-preview.102.
- Ensure authentication headers are correctly scrubbed.
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