Credential disclosure via case-mismatched redirect scrub
Published Jun 19, 2026 · Updated Jun 19, 2026
Information disclosure in Microsoft kiota-typescript before 1.0.0-preview.102 allows attackers to steal credentials via cross-origin redirects. RedirectHandlerOptions deletes mixed-case Authorization and Cookie properties after FetchRequestAdapter has lower-cased the header keys, so the scrub removes nothing. The default middleware chain forwards Bearer tokens or session cookies when an upstream server, man-in-the-middle attackers, or an attacker-influenced base URL supplies a 30x redirect to another origin.
Summary
What happened
Information disclosure in Microsoft kiota-typescript before 1.0.0-preview.102 allows attackers to steal credentials via cross-origin redirects. RedirectHandlerOptions deletes mixed-case Authorization and Cookie properties after FetchRequestAdapter has lower-cased the header keys, so the scrub removes nothing. The default middleware chain forwards Bearer tokens or session cookies when an upstream server, man-in-the-middle attackers, or an attacker-influenced base URL supplies a 30x redirect to another origin.
The record
- CVE
- CVE-2026-49336
- Published
- Jun 19, 2026
- Updated
- Jun 19, 2026
- Vendor
- Microsoft
- Product
- kiota-typescript
- Classifications
- CWE-178, CWE-200, T1539, T1528
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 19, 2026CVE publishedPublication date reported by the CVE source.
- Jun 19, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=>= 1.0.0-preview.97, < 1.0.0-preview.102
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- End-to-end cross-origin credential leak proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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