CVE-2026-23527
h3 v1 has Request Smuggling (TE.TE) issue
CVSS Score
8.9
EPSS Score
0.0%
EPSS Percentile
9th
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.
| CWE | CWE-444 |
| Vendor | h3js |
| Product | h3 |
| Published | Jan 15, 2026 |
| Last Updated | Apr 13, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:L Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
Low
Affected Versions
h3js / h3
< 1.15.5
References
github.com: https://github.com/h3js/h3/security/advisories/GHSA-mp2g-9vg9-f4cg github.com: https://github.com/h3js/h3/commit/618ccf4f37b8b6148bea7f36040471af45bfb097 github.com: https://github.com/h3js/h3/releases/tag/v1.15.5 simonkoeck.com: https://simonkoeck.com/writeups/h3-transfer-encoding-request-smuggling