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CVE-2026-23527 - H3 Plugin

CVE-2026-23527

Vulnerability CVE-2026-23527 PLUGIN h3 HIGH

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.

CVE-2026-23527

HIGH CVSS 8.9 Published 2026-01-15 Updated 2026-01-23
AI Risk Critical (99/100) Active Exploit: Likely Published Exploit: Public exploit references found Priority: P1 Immediate
Severity Band HIGH
CVSS Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:L
Affected Components 1
Reference Links 2
AI Risk Engine Critical (99/100)
Exploitability High
Active Exploitation Likely
Published Exploit Status Public exploit references found

Threat Timeline

  1. 2026-01-15 CVE published and first recorded in the threat feed.
  2. 2026-01-23 Record updated with latest vulnerability metadata.
  3. 2026-04-09 AI technical context refreshed for mitigation and impact guidance.
  4. Now Monitoring for follow-up changes, linked references, and new related CVEs.

AI Context

Machine-generated threat intelligence

AI Updated 12 days ago

AI enriched 12 days ago (2026-04-09 06:51 UTC)

Technical Summary

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.

Potential Impact

Severity is HIGH (CVSS 8.9). Depending on deployment context, affected components may be exposed to unauthorized actions or data integrity risk.

Exploitability Assessment

Exploitability is assessed as High based on published exploit references.

Primary risk drivers: published exploit references

Mitigation Recommendations

Validate affected product versions, prioritize patching, and monitor references for vendor remediation guidance. If immediate patching is not possible, apply compensating controls and limit exposure of vulnerable surfaces.

Detection & Monitoring

Track authentication anomalies, unexpected file writes, and suspicious plugin API activity around affected components.

Business Impact Lens

Prioritize remediation where affected components process customer data, admin sessions, or Internet-exposed workflows.

Affected Products

H3 PLUGIN · h3 Affected: >= 1.15.5, < 1.15.5 Fixed in: 1.15.5
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