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CVE-2025-59139
September 12, 2025
Hono is a Web application framework that provides support for any JavaScript runtime. In versions prior to 4.9.7, a flaw in the "bodyLimit" middleware could allow bypassing the configured request body size limit when conflicting HTTP headers were present. The middleware previously prioritized the "Content-Length" header even when a "Transfer-Encoding: chunked" header was also included. According to the HTTP specification, "Content-Length" must be ignored in such cases. This discrepancy could allow oversized request bodies to bypass the configured limit. Most standards-compliant runtimes and reverse proxies may reject such malformed requests with "400 Bad Request", so the practical impact depends on the runtime and deployment environment. If body size limits are used as a safeguard against large or malicious requests, this flaw could allow attackers to send oversized request bodies. The primary risk is denial of service (DoS) due to excessive memory or CPU consumption when handling very large requests. The implementation has been updated to align with the HTTP specification, ensuring that "Transfer-Encoding" takes precedence over "Content-Length". The issue is fixed in Hono v4.9.7, and all users should upgrade immediately.
Affected Packages
https://github.com/honojs/hono.git (GITHUB):
Affected version(s) >=v0.0.1 <v4.9.7
Fix Suggestion:
Update to version v4.9.7
hono (NPM):
Affected version(s) >=0.0.1 <4.9.7
Fix Suggestion:
Update to version 4.9.7
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CVSS v4
Base Score:
6.9
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
LOW
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
5.3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
LOW
Weakness Type (CWE)
Allocation of Resources Without Limits or Throttling
Uncontrolled Resource Consumption
EPSS
Base Score:
0.14