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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

7.0 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N · score source

EPSS

• CVE-2026-44503: 0.64% estimated exploitation activity in the next 30 days; percentile 50.83 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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…

Published by the source

7 May 2026, 01:49 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

26 Oct 2026, 13:01 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-7j59-v9qr-6fq9

2. Revision 2 · amended · 24 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-7j59-v9qr-6fq9

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# Patch Next advisory brief: CVE-2026-44503

Advisory: Kiota abstractions RedirectHandler leaks Cookie/Proxy-Authorization headers on cross-host redirect
IDs: CVE-2026-44503, GHSA-7j59-v9qr-6fq9
Record: https://patchnext.com/advisories/cve-2026-44503 (revision 3, source checked 26 Oct 2026, 13:01 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.0)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/microsoft/kiota-http-go 1.5.5; kiota-typescript 1.0.0-preview.100; microsoft-kiota-http 1.9.9; microsoft.kiota.abstractions 1.22.0; com.microsoft.kiota:microsoft-kiota-abstractions 1.9.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/microsoft/kiota-http-go: affected < 1.5.5; fixed in 1.5.5
- npm kiota-typescript: affected < 1.0.0-preview.100; fixed in 1.0.0-preview.100
- PyPI microsoft-kiota-http: affected < 1.9.9; fixed in 1.9.9
- NuGet microsoft.kiota.abstractions: affected < 1.22.0; fixed in 1.22.0
- Maven com.microsoft.kiota:microsoft-kiota-abstractions: affected < 1.9.1; fixed in 1.9.1

## Suggested inspection (read-only)
- Go github.com/microsoft/kiota-http-go: check the installed version with your package manager.
- `npm ls kiota-typescript --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.
- `python -m pip show microsoft-kiota-http`: prints the installed version. Run with the environment that serves production active.
- NuGet microsoft.kiota.abstractions: check the installed version with your package manager.
- Maven com.microsoft.kiota:microsoft-kiota-abstractions: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/microsoft/kiota-http-go, kiota-typescript, microsoft-kiota-http, microsoft.kiota.abstractions, com.microsoft.kiota:microsoft-kiota-abstractions.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-7j59-v9qr-6fq9 (OSV record GHSA-7j59-v9qr-6fq9 lists affected ranges: Maven com.microsoft.kiota:microsoft-kiota-abstractions >=0 =0 =0 =0 =0 <1.5.5 (fixed))
- Verified: https://github.com/advisories/GHSA-7j59-v9qr-6fq9 (GitHub-reviewed advisory GHSA-7j59-v9qr-6fq9 lists affected ranges: Maven com.microsoft.kiota:microsoft-kiota-abstractions >=0 =0 =0 =0 =0 <1.5.5)

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