h3 v1 has Request Smuggling (TE.TE) issue

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Summary

CVECVE-2026-23527
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-01-15 20:16:05 UTC
Updated2026-04-13 17:16:27 UTC
DescriptionH3 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.

Risk And Classification

Primary CVSS: v3.1 9.8 CRITICAL from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.000370000 probability, percentile 0.109040000 (date 2026-04-15)

Problem Types: CWE-444 | CWE-444 CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.1[email protected]Secondary8.9HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:L
3.1CNADECLARED8.9HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:L

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application H3 H3 All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA H3js H3 affected < 1.15.5 Not specified

References

ReferenceSourceLinkTags
github.com/h3js/h3/commit/618ccf4f37b8b6148bea7f36040471af45bfb097 [email protected] github.com Patch
github.com/h3js/h3/releases/tag/v1.15.5 [email protected] github.com
github.com/h3js/h3/security/advisories/GHSA-mp2g-9vg9-f4cg [email protected] github.com Exploit, Vendor Advisory
simonkoeck.com/writeups/h3-transfer-encoding-request-smuggling [email protected] simonkoeck.com
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