CVE-2026-23527
January 15, 2026
H3 is a minimal H(TTP) framework built for high performance and portability. Prior to 1.15.5, there is a critical HTTP Request Smuggling vulnerability. readRawBody is doing a strict case-sensitive check for the Transfer-Encoding header. It explicitly looks for "chunked", but per the RFC, this header should be case-insensitive. This vulnerability is fixed in 1.15.5.
Affected Packages
https://github.com/h3js/h3.git (GITHUB):
Affected version(s) >=v0.0.1 <v1.15.5Fix Suggestion:
Update to version v1.15.5h3 (NPM):
Affected version(s) >=0.2.0 <1.15.5Fix Suggestion:
Update to version 1.15.5Related Resources (5)
Do you need more information?
Contact UsCVSS v4
Base Score:
9.5
Attack Vector
NETWORK
Attack Complexity
HIGH
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
HIGH
Vulnerable System Integrity
HIGH
Vulnerable System Availability
LOW
Subsequent System Confidentiality
HIGH
Subsequent System Integrity
HIGH
Subsequent System Availability
LOW
CVSS v3
Base Score:
8.9
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
LOW
Weakness Type (CWE)
Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
EPSS
Base Score:
0.1
