Vulnerability · Published Jan 13, 2026 · Assigned by GitHub_M

CVE-2026-22817JWT Algorithm Confusion via Unsafe Default (HS256) in Hono JWT Middleware Allows Token Forgery and Auth Bypass

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 0.2% (higher than 6% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)8.2High

Exploit odds (30 days)0.2%top 94.1% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

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 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 packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
npm	hono	4.11.4	GHSA-f67f-6cw9-8mq4

Affected products (as reported)

Vendor	Product	Versions
honojs	hono	< 4.11.4

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-f67f-6cw9-8mq4 x_refsource_CONFIRM
https://github.com/honojs/hono/commit/cc0aa7ae327ed84cc391d29086dec2a3e44e7a1f x_refsource_MISC