CVE-2026-47673: hono Improper Authorization

Vulnerability summary

CVE-2026-47673 is a medium (CVSS 6.5) Improper Authorization vulnerability in hono. EPSS estimates a 0.20% chance of exploitation in the next 30 days, higher than 9% of scored vulnerabilities.

Timeline

1. 28-05-2026
   PublishedVulnerability first disclosed.
2. 30-05-2026
   Last modifiedVulnerability information updated.

Description

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.21, the jwt and jwk middlewares do not verify that the Authorization header value uses theBearer scheme. Any two-part header value — regardless of the scheme name in the first position — proceeds to JWT verification. A request presenting a valid JWT under a non-Bearer scheme identifier (such as Basic or Token) is authenticated identically to a correctly formed Bearer request. This vulnerability is fixed in 4.12.21.

• CWE-285Improper AuthorizationThe product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action.