Kaitai Struct: compiler vulnerable to denial-of-service (DoS)


Kaitai Struct: compiler provided by Kaitai team contains SnakeYAML library version 1.25, which is used in parsing .ksy files.
SnakeYAML version 1.25 expands recursive aliases unlimitedly (CWE-674), hence Katai Struct: compiler is vulnerable to a denial-of-service (DoS) attack by Billion Laughs Attack.

Taichi Kotake of Sterra Security Co.,Ltd. / Akatsuki Games Inc. reported this vulnerability to IPA.
JPCERT/CC coordinated with the developer under Information Security Early Warning Partnership.
CVSS Severity (What is CVSS?)

CVSS V3 Severity:
Base Metrics 5.5 (Medium) [IPA Score]
  • Attack Vector: Local
  • Attack Complexity: Low
  • Privileges Required: None
  • User Interaction: Required
  • Scope: Unchanged
  • Confidentiality Impact: None
  • Integrity Impact: None
  • Availability Impact: High
CVSS V2 Severity:
Base Metrics 4.3 (Medium) [IPA Score]
  • Access Vector: Network
  • Access Complexity: Medium
  • Authentication: None
  • Confidentiality Impact: None
  • Integrity Impact: None
  • Availability Impact: Partial
Affected Products

Kaitai team
  • Kaitai Struct: compiler 0.9 and earlier


Processing untrusted .ksy files may cause a denial-of-service (DoS) condition.

[Update the software]
Update the software to the latest version according to the information provided by the developer.
According to the developer, this vulnerability has been fixed at version 0.10 by updating the bundled SnakeYAML library.
Vendor Information

Kaitai team
CWE (What is CWE?)

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

  1. CVE-2017-18640

  1. JVN : JVN#42883072
  2. Related document : Preventing YAML parsing vulnerabilities with snakeyaml in Java
Revision History

  • [2022/08/04]
      Web page was published