Scheme-based policy bypass via unchecked authorization prefix
Published May 28, 2026 · Updated May 28, 2026
Improper authorization in Hono before 4.12.21 allows remote attackers with a valid JWT to bypass scheme-based network controls. The jwt and jwk middleware split an Authorization or custom header on whitespace and verify the second token without requiring the first token to equal Bearer. Exploitation requires a valid JWT and an application that relies on a WAF, API gateway, or reverse proxy to enforce scheme-specific policy; accepted requests receive the token's normal access.
Summary
What happened
Improper authorization in Hono before 4.12.21 allows remote attackers with a valid JWT to bypass scheme-based network controls. The jwt and jwk middleware split an Authorization or custom header on whitespace and verify the second token without requiring the first token to equal Bearer. Exploitation requires a valid JWT and an application that relies on a WAF, API gateway, or reverse proxy to enforce scheme-specific policy; accepted requests receive the token's normal access.
The record
- CVE
- CVE-2026-47673
- Published
- May 28, 2026
- Updated
- May 28, 2026
- Vendor
- Hono
- Product
- Hono
- Classifications
- CWE-285, T1078
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- May 28, 2026CVE publishedPublication date reported by the CVE source.
- May 28, 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?
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- Affected versionversion=< 4.12.21
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Public exploit references
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Technologies
Your stack
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Your stack
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