Credential disclosure via incomplete cross-origin header scrubbing
Published May 14, 2026 · Updated May 14, 2026
Sensitive-header disclosure in Microsoft Kiota RedirectHandler libraries allows remote attackers to capture credentials via cross-origin redirects. The handler removes only Authorization when a 3xx response changes host or scheme, forwarding Cookie, Proxy-Authorization, and custom headers. Exploitation requires control of a redirect destination or traffic-routing condition; exposed session cookies, proxy credentials, and API keys can be reused.
Summary
What happened
Sensitive-header disclosure in Microsoft Kiota RedirectHandler libraries allows remote attackers to capture credentials via cross-origin redirects. The handler removes only Authorization when a 3xx response changes host or scheme, forwarding Cookie, Proxy-Authorization, and custom headers. Exploitation requires control of a redirect destination or traffic-routing condition; exposed session cookies, proxy credentials, and API keys can be reused.
The record
- CVE
- CVE-2026-44503
- Published
- May 14, 2026
- Updated
- May 14, 2026
- Vendor
- Microsoft
- Product
- kiota-java
- Classifications
- CWE-601, CAPEC-178, T1539
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 14, 2026CVE publishedPublication date reported by the CVE source.
- May 14, 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=< 1.9.1
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
- SecurityPoC cross-host redirect testproof 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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