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.
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.
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.
## Summary
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.
## Details
The vulnerability exists in two components:
1. **Permissive regex pattern:** The `IPV4_REGEX (/^[0-9]{0,3}\.[0-9]{0,3}\.[0-9]{0,3}\.[0-9]{0,3}$/)` accepts octet values greater than 255 (e.g., `999`).
2. **Unsafe binary conversion:** The `convertIPv4ToBinary` function does not validate octet ranges before performing bitwise operations. When an octet exceeds 255, it overflows into adjacent octets during the bit-shift calculation.
For example, the IP address `1.2.2.355` is accepted and converts to the same binary value as 1.2.3.99:
* `355` = `256 + 99` = `0x163`
* After bit-shifting: `(1 << 24) + (2 << 16) + (2 << 8) + 355` = `0x01020363` = `1.2.3.99`
## Impact
An attacker can bypass IP-based restrictions by crafting malformed IP addresses:
* **Blocklist bypass:** If `1.2.3.0/24` is blocked, an attacker can use `1.2.2.355` (or similar) to bypass the restriction.
* **Allowlist bypass:** Requests from unauthorized IP ranges may be incorrectly permitted.
This is exploitable when the application relies on client-provided IP addresses (e.g., `X-Forwarded-For header`) for access control decisions.
## Affected Components
* IP Restriction Middleware
* `src/utils/ipaddr.ts`: `IPV4_REGEX`, `convertIPv4ToBinary`, `distinctRemoteAddr`
EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON.
Original publisher date fields
datePublished: Jan 27, 2026, 7:06:42 PM
dateUpdated: Jan 27, 2026, 7:20:35 PM
1 related source bulletins · separate from aliases
WID-SEC-W-2026-0574: IBM App Connect Enterprise: Mehrere Schwachstellen
No normalized affected-package data is projected for this source revision. The original publisher record may contain additional product and version evidence; this does not establish that a package is unaffected.
NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON.
Source analysis status: Analyzed
Weakness classifications: CWE-185
Original publisher date fields
published: 2026-01-27T19:16:16.363
lastModified: 2026-06-17T10:23:00.350
1 source CPE criteria · context only
cpe:2.3:a:hono:hono:*:*:*:*:*:node.js:*:*
The original JSON retains the logical configuration operators, exclusions and version bounds.
No normalized affected-package data is projected for this source revision. The original publisher record may contain additional product and version evidence; this does not establish that a package is unaffected.