CVE-2026-24398 Hono's IPv4 address validation bypass in IP Restriction Middleware allows IP spoofing

What is CVE-2026-24398?

CVE-2026-24398 is a medium-severity vulnerability in honojs hono, published on 27 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to version 4.11.7, IP Restriction Middleware in Hono is vulnerable to an IP address validation bypass. The `IPV4_REGEX` pattern and `convertIPv4ToBinary` function in `src/utils/ipaddr.ts` do not properly validate that IPv4 octet values are within the valid range of 0-255, allowing attackers to craft malformed IP addresses that bypass IP-based access controls. Version 4.11.7 contains a patch for the issue.

Weakness: CWE-185

Which versions are affected by CVE-2026-24398?

2 open source packages ship an affected version, including hono. It affects 1 product.

Products include Hono Hono.

How do I fix CVE-2026-24398?

Upgrade hono to 4.11.7 or later.

Is CVE-2026-24398 being exploited?

There is no known exploitation of CVE-2026-24398 in the wild and no public exploit code.

Other vulnerabilities in honojs hono

• CVE-2026-27700 Hono is Vulnerable to Authentication Bypass by IP Spoofing in AWS Lambda ALB conninfo High 8.2
• CVE-2026-22817 JWT Algorithm Confusion via Unsafe Default (HS256) in Hono JWT Middleware Allows Token Forgery and Auth Bypass High 8.2
• CVE-2026-22818 JWT algorithm confusion in Hono JWK Auth Middleware when JWK lacks "alg" (untrusted header.alg fallback) High 8.2
• CVE-2025-62610 Hono Improperly Authorizes JWT Audience Validation High 8.1
• CVE-2026-29045 Hono: Arbitrary file access via serveStatic vulnerability High 7.5

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-r354-f388-2fhh, MINI-36v9-2vpp-9634, MINI-6x7x-4jhm-j5c5.