Vulnerability · Published Jan 13, 2026 · Assigned by GitHub_M
CVE-2026-22818JWT algorithm confusion in Hono JWK Auth Middleware when JWK lacks "alg" (untrusted header.alg fallback)
High 8.2
In plain English
A high-severity security flaw in hono from honojs. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 3% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | hono | 4.11.4 | GHSA-3vhc-576x-3qv4 |
Affected products (as reported)
Weakness: CWE-347 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N
References
- https://github.com/honojs/hono/security/advisories/GHSA-3vhc-576x-3qv4 x_refsource_CONFIRM
- https://github.com/honojs/hono/commit/190f6e28e2ca85ce3d1f2f54db1310f5f3eab134 x_refsource_MISC