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CVE-2026-49336— @microsoft/kiota-http-fetchlibrary: Bearer token and Cookie leak across origin on redirect due to case-mismatched scrub in fetchRequestAdapter

Quick assessment

Affected
microsoft kiota-typescript
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Microsoft kiota-typescript是美国Microsoft公司的根据产品名称和生成代码的上下文,这是一个用于生成TypeScript客户端代码的库。 Microsoft kiota-typescript 1.0.0-preview.97版本至1.0.0-preview.101版本存在输入验证错误漏洞，该漏洞可导致Cookie泄露。

AI Predicted 7.4 Difficulty: Trivial EPSS 1.18% · P66

Possible ATT&CK Techniques 1 AI

T1557 · Adversary-in-the-Middle

Affected Version Matrix 1

VendorProduct Version RangeStatus
microsoft kiota-typescript >= 1.0.0-preview.97, < 1.0.0-preview.102 affected
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I. Basic Information for CVE-2026-49336

Vulnerability Information
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Vulnerability Title
@microsoft/kiota-http-fetchlibrary: Bearer token and Cookie leak across origin on redirect due to case-mismatched scrub in fetchRequestAdapter
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P
Source: CVE Program / CVE List V5
Vulnerability Type
大小写敏感处理不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
Microsoft kiota-typescript 输入验证错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Microsoft kiota-typescript是美国Microsoft公司的根据产品名称和生成代码的上下文,这是一个用于生成TypeScript客户端代码的库。 Microsoft kiota-typescript 1.0.0-preview.97版本至1.0.0-preview.101版本存在输入验证错误漏洞，该漏洞可导致Cookie泄露。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
microsoft kiota-typescript >= 1.0.0-preview.97, < 1.0.0-preview.102 -

II. Public POCs for CVE-2026-49336

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III. Intelligence Information for CVE-2026-49336

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Patches & Fixes for CVE-2026-49336 (1)

Vendor Advisories for CVE-2026-49336 (1)

Same Patch Batch · microsoft · 2026-06-19 · 8 CVEs total

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IV. Related Vulnerabilities

Same vendor: microsoft
Same weakness: CWE-178

V. Comments for CVE-2026-49336

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