Man-in-the-Middle (MitM) Affecting yarn package, versions <1.17.3



    Exploit Maturity Proof of concept
    Attack Complexity High
    User Interaction Required
    Scope Changed
    Confidentiality High
    Availability High
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8.1 high

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  • Snyk ID SNYK-JS-YARN-451571
  • published 15 Jul 2019
  • disclosed 12 Jul 2019
  • credit Сковорода Никита Андреевич

How to fix?

Upgrade yarn to version 1.17.3 or higher.


yarn is a package for dependency management.

Affected versions of this package are vulnerable to Man-in-the-Middle (MitM). Npm credentials such as _authToken were found to be sent over clear text when processing scoped packages that are listed as resolved. This could allow a suitably positioned attacker to eavesdrop and compromise the sent credentials.