Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.11.4, there is a flaw in Hono’s JWK/JWKS JWT verification middleware allowed the algorithm specified in the JWT header to influence signature verification when the selected JWK did not explicitly define an algorithm. This could enable JWT algorithm confusion and, in certain configurations, allow forged tokens to be accepted. The JWK/JWKS JWT verification middleware has been updated to require an explicit allowlist of asymmetric algorithms when verifying tokens. The middleware no longer derives the verification algorithm from untrusted JWT header values. This vulnerability is fixed in 4.11.4.

Affected: npm: hono

## Summary

A flaw in Hono’s JWK/JWKS JWT verification middleware allowed the algorithm specified in the JWT header to influence signature verification when the selected JWK did not explicitly define an algorithm. This could enable JWT algorithm confusion and, in certain configurations, allow forged tokens to be accepted.

## Details

When verifying JWTs using JWKs or a JWKS endpoint, the middleware selected the verification algorithm based on the JWK’s `alg` field if present. If the JWK did not specify an algorithm, the middleware fell back to using the `alg` value provided in the unverified JWT header.

Because the `alg` field in a JWK is optional and commonly omitted in real-world JWKS configurations, this behavior could allow an attacker to influence which algorithm is used for verification. In some environments, this may result in authentication or authorization bypass through crafted JWTs.

The practical impact depends on application configuration, including which algorithms are accepted and how JWTs are used to make authorization decisions.

## Impact

In affected configurations, an attacker may be able to forge JWTs with attacker-controlled claims, potentially leading to authentication or authorization bypass.

Applications that do not use the JWK/JWKS middleware, do not rely on JWT-based authentication, or explicitly restrict allowed algorithms are not affected.

## Resolution

Update to the latest patched release.

**Breaking change:**

The JWK/JWKS JWT verificatio…

Ein Angreifer kann mehrere Schwachstellen in IBM App Connect Enterprise Certified Container ausnutzen, um beliebigen Programmcode auszuführen, einen Denial-of-Service-Zustand zu verursachen, die Authentifizierung zu umgehen, vertrauliche Informationen zu manipulieren oder offenzulegen.