CVE-2026-24398 in hono
Summary
by MITRE • 01/27/2026
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.
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Analysis
by VulDB Data Team • 03/03/2026
The vulnerability identified as CVE-2026-24398 affects the Hono web application framework, a JavaScript-based framework designed to support multiple runtime environments. This security flaw specifically targets the IP Restriction Middleware component that is responsible for implementing access controls based on IP addresses. The issue represents a critical weakness in the framework's ability to enforce network-level security policies, potentially allowing unauthorized access to applications that rely on IP-based restrictions for protection. The vulnerability impacts versions prior to 4.11.7, making it essential for developers and system administrators to assess their current deployments and apply the necessary patch.
The technical root cause of this vulnerability lies within the implementation of IPv4 address validation logic in the `src/utils/ipaddr.ts` file. The `IPV4_REGEX` pattern and `convertIPv4ToBinary` function fail to properly validate that each octet of an IPv4 address falls within the valid range of 0-255. This validation gap creates a path where attackers can construct malformed IP addresses that appear to be valid but contain octet values outside the acceptable range. The bypass occurs because the validation functions do not enforce the fundamental constraint that IPv4 octets must be integers between 0 and 255, allowing malicious input to pass through the access control mechanisms. This flaw directly corresponds to CWE-20, which addresses improper input validation, and demonstrates how inadequate validation of numerical ranges can lead to security vulnerabilities.
The operational impact of this vulnerability is significant, as it undermines the integrity of IP-based access controls that many applications rely upon for security. Attackers can exploit this weakness to bypass network-level restrictions that are meant to limit access to sensitive resources or administrative interfaces. This could enable unauthorized users to gain access to restricted application features, potentially leading to data breaches, privilege escalation, or other malicious activities. The vulnerability affects any application using Hono's IP Restriction Middleware where access control is implemented based on IP addresses, making it particularly concerning for web applications that depend on network-level security measures as part of their defense-in-depth strategy. The bypass capability represents a direct threat to the principle of least privilege, as it allows attackers to circumvent intended access restrictions.
Mitigation of this vulnerability requires immediate deployment of version 4.11.7, which contains the necessary patch to address the IP address validation bypass. System administrators should conduct comprehensive assessments of their Hono-based applications to identify all instances where IP Restriction Middleware is implemented and ensure proper patching across all environments. Additionally, organizations should review their overall IP-based access control policies and consider implementing redundant security measures such as authentication mechanisms, rate limiting, and additional network segmentation. From an ATT&CK framework perspective, this vulnerability relates to T1071.004 (Application Layer Protocol: DNS) and T1566 (Phishing) as attackers may leverage the bypass to gain initial access, while T1562.004 (Impair Defenses: Disable or Modify Tools) could be relevant if network security tools are bypassed through this vulnerability. Organizations should also consider implementing network monitoring to detect anomalous access patterns that might indicate exploitation attempts. The patch addresses the core validation logic and ensures that all IPv4 octet values are properly constrained within the valid range, thereby restoring the intended security controls for IP-based access restrictions.