High severity8.9NVD Advisory· Published Jan 15, 2026· Updated Apr 13, 2026
CVE-2026-23527
CVE-2026-23527
Description
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.
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Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
h3npm | < 1.15.5 | 1.15.5 |
Affected products
1Patches
Vulnerability mechanics
References
6- github.com/h3js/h3/commit/618ccf4f37b8b6148bea7f36040471af45bfb097nvdPatchWEB
- github.com/h3js/h3/security/advisories/GHSA-mp2g-9vg9-f4cgnvdExploitVendor AdvisoryWEB
- github.com/advisories/GHSA-mp2g-9vg9-f4cgghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2026-23527ghsaADVISORY
- github.com/h3js/h3/releases/tag/v1.15.5nvdWEB
- simonkoeck.com/writeups/h3-transfer-encoding-request-smugglingnvdWEB
News mentions
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