H2O vulnerable to HTTP header injection


H2O is an open source web server software. H2O contains an HTTP header injection vulnerability.

Kazuho Oku reported this vulnerability to IPA to notify users of its solution through JVN. JPCERT/CC and Kazuho Oku coordinated under the Information Security Early Warning Partnership.
CVSS Severity (What is CVSS?)

CVSS V3 Severity:
Base Metrics 3.4 (Low) [IPA Score]
  • Attack Vector: Network
  • Attack Complexity: High
  • Privileges Required: None
  • User Interaction: Required
  • Scope: Changed
  • Confidentiality Impact: None
  • Integrity Impact: Low
  • Availability Impact: None
CVSS V2 Severity:
Base Metrics 4.3 (Medium) [IPA Score]
  • Access Vector: Network
  • Access Complexity: Medium
  • Authentication: None
  • Confidentiality Impact: None
  • Integrity Impact: Partial
  • Availability Impact: None
Affected Products

Kazuho Oku
  • H2O version 1.6.1 and earlier
  • H2O version 1.7.0-beta2 and earlier

The above versions when configured to use the redirect handler on the server are vulnerable.

An HTTP response splitting attack may result in arbitrary cookie values.

[Update the Software]
Update to the latest version according to the information provided by the developer.
Vendor Information

Kazuho Oku
CWE (What is CWE?)

  1. Improper Input Validation(CWE-20) [IPA Evaluation]
CVE (What is CVE?)

  1. CVE-2016-1133

  1. JVN : JVN#45928828
  2. National Vulnerability Database (NVD) : CVE-2016-1133
Revision History

  • [2016/01/15]
      Web page was published
      Vendor Information : Contents were added
      References : Content was added