CVE-2026-23527CRITICAL 9.8EPSS p42.9%

CVE-2026-23527CVE-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.

Scoring

CVSS 3.19.8 (CRITICAL)
VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS0.58% probability of exploitation · percentile 42.9% · 2026-06-18T12:00:27Z
Published2026-01-15
Last modified2026-04-13

Underlying weaknesses· 1

CWE-444

References

  1. https://github.com/h3js/h3/commit/618ccf4f37b8b6148bea7f36040471af45bfb097
  2. https://github.com/h3js/h3/releases/tag/v1.15.5
  3. https://github.com/h3js/h3/security/advisories/GHSA-mp2g-9vg9-f4cg
  4. https://simonkoeck.com/writeups/h3-transfer-encoding-request-smuggling

1

TypeTargetConfidenceTier
WeaknessInconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')cwe-4440%live

Related by meaning· 6

Nearest entities by semantic similarity across the cs-graph corpus.

CVE
CVE-2026-33131
CVE
CVE-2026-33128
CVE
CVE-2025-43859
CVE
CVE-2026-2332
CVE
CVE-2026-28368
CVE
CVE-2026-42581
Sourced from NVD + FIRST.org EPSS. Curated for EU compliance use cases by Adam Lundqvist, Founder at SQUR.