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 JWT header’s alg value to influence signature verification when the selected JWK did not explicitly specify an algorithm. This could enable JWT algorithm confusion and, in certain configurations, allow forged tokens to be accepted. As part of this fix, the JWT middleware now requires the alg option to be explicitly specified. This prevents algorithm confusion by ensuring that the verification algorithm is not derived 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 JWT header’s `alg` value to influence signature verification when the selected JWK did not explicitly specify 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, but otherwise fell back to the `alg` value provided in the unverified JWT header.

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

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

## Impact

In affected configurations, an attacker may be able to forge JWTs with attacker-controlled claims, potentially resulting in 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:**

As part of this fix, the JWT middleware now requires the `alg` option to be explicitly specified…

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.