Vulnerability in @microsoft/kiota-http-fetchlibrary (CVE-2026-49336)
Summary
Vulnerability in @microsoft/kiota-http-fetchlibrary (CVE-2026-49336). Risk of unauthorized operations or information disclosure. Exploitable via Authorization header. Mitigation: upgrade to 1.0.0-preview.102 or later.
Original description
The description as published by the source.
@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.
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-49336 has been found in @microsoft/kiota-http-fetchlibrary.
Attackers can target a specific entry point like Authorization header over the network to misuse the product.
Risk of unauthorized operations or information disclosure.
What to do: upgrade @microsoft/kiota-http-fetchlibrary to 1.0.0-preview.102 or later.
If unsure, ask your IT team or search "@microsoft/kiota-http-fetchlibrary CVE-2026-49336" on the vendor's site.
CVE-2026-49336 (@microsoft/kiota-http-fetchlibrary) — CWE-178
Attack surface: Authorization header / Cookie header / RedirectHandler / Authorization
Patched: 1.0.0-preview.102 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-178) exists in @microsoft/kiota-http-fetchlibrary. Attackers reach the vulnerable code path via Authorization header.
Check the vendor advisory for the affected versions of @microsoft/kiota-http-fetchlibrary. Attack surface: Authorization header / Cookie header / RedirectHandler / Authorization.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to 1.0.0-preview.102.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r '@microsoft/kiota-http-fetchlibrary' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r '@microsoft/kiota-http-fetchlibrary' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
@microsoft/kiota-http-fetchlibraryを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade @microsoft/kiota-http-fetchlibrary to 1.0.0-preview.102ステージング環境で 1.0.0-preview.102 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory github.com
- advisory nvd.nist.gov
- advisory github.com
- patch github.com
- web github.com