Skip to main content
VulnerabilityPublished Updated

CVE-2026-49336: microsoft kiota-typescript · Improper Handling of Case Sensitivity

Affects microsoft kiota-typescriptSource CVE Database V5

0
Compare

Public exploit available · CVSS 5.5 Medium : upgrade to 1.0.0-preview.102 as a priority.

Data as of 1 Nov 2026, 22:58 UTC

CVSS 4.0 base score
5.5Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.7% chance of exploitation in 30 days – higher than 54% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 1.0.0-preview.102
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

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 19 Jun 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: evidence found.

    CVSS exploit maturity: proof of concept public

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CVSS vector, the Metasploit, Exploit-DB and nuclei-templates index as of 1 Nov 2026.

What to do

Upgrade microsoft kiota-typescript to 1.0.0-preview.102.

Affected software

ProductAffectedFixed in
microsoftkiota-typescriptAffected
  • >=1.0.0-preview.97 <1.0.0-preview.102
Fixed in
  • 1.0.0-preview.102
npm@microsoft/kiota-http-fetchlibrarypkg:npm/@microsoft/kiota-http-fetchlibraryOther threatsAffected
  • >=1.0.0-preview.97 <=1.0.0-preview.101
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade to @microsoft/kiota-http-fetchlibrary version 1.0.0-preview.102 or later, where the issue is patched. Until upgraded, be aware that the default middleware does not properly strip sensitive headers on redirects, so consider implementing custom middleware to correctly handle header scrubbing or avoid using affected versions in sensitive environments. Patch status is not explicitly confirmed in the vendor advisory, but the description states version 1.0.0-preview.102 patches the issue.

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.

References

Community reviews

Loading reviews…