{"id":"CVE-2026-49336","aliases":["GHSA-396q-4vc8-28x9"],"url":"https://o3.security/vulnerability/CVE-2026-49336","summary":"@microsoft/kiota-http-fetchlibrary: Bearer token and Cookie leak across origin on redirect due to case-mismatched scrub in fetchRequestAdapter","details":"@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.","published":"2026-06-19T18:19:03.222Z","modified":"2026-08-12T03:51:20.049300607Z","cvss":null,"epss":{"score":0.01178,"percentile":0.65598,"asOf":"2026-09-07"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"@microsoft/kiota-http-fetchlibrary","fixedVersion":"1.0.0-preview.102"}],"fix":{"url":"https://github.com/microsoft/kiota-typescript/commit/09f8bd9b34d68bf412a9b78f6ca7e7961ef14974","label":"microsoft/kiota-typescript@09f8bd9"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/49xxx/CVE-2026-49336.json"},{"type":"ADVISORY","url":"https://github.com/microsoft/kiota-typescript/security/advisories/GHSA-396q-4vc8-28x9"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-49336"},{"type":"FIX","url":"https://github.com/microsoft/kiota-typescript/commit/09f8bd9b34d68bf412a9b78f6ca7e7961ef14974"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:20.049300607Z"}}