Cybozu KUNAI App fails to verify SSL server certificates


Cybozu KUNAI App provided by Cybozu, Inc. fails to verify SSL server certificates.

Kusano Kazuhiko reported this vulnerability to the developer.
JPCERT/CC coordinated with the developer under Information Security Early Warning Partnership.
CVSS Severity (What is CVSS?)

CVSS V3 Severity:
Base Metrics 4.8 (Medium) [IPA Score]
  • Attack Vector: Network
  • Attack Complexity: High
  • Privileges Required: None
  • User Interaction: None
  • Scope: Unchanged
  • Confidentiality Impact: Low
  • Integrity Impact: Low
  • Availability Impact: None
CVSS V2 Severity:
Base Metrics 4.0 (Medium) [IPA Score]
  • Access Vector: Network
  • Access Complexity: High
  • Authentication: None
  • Confidentiality Impact: Partial
  • Integrity Impact: Partial
  • Availability Impact: None
Affected Products

Cybozu, Inc.
  • Cybozu KUNAI for Android 2.1.2 to 3.0.4
  • Cybozu KUNAI for iPhone 2.0.3 to 3.1.5


A man-in-the-middle attack may allow an attacker to eavesdrop on an encrypted communication.

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

Cybozu, Inc.
CWE (What is CWE?)

  1. No Mapping(CWE-Other) [IPA Evaluation]
CVE (What is CVE?)

  1. CVE-2016-1187

  1. JVN : JVN#11994518
  2. National Vulnerability Database (NVD) : CVE-2016-1187
Revision History

  • [2016/05/16]
      Web page was published
      Vendor Information : Content was modified
      References : Content was modified
      References : Content was added