Non-Constant Time String Comparison Affecting cookie-signature package, versions <1.0.4



    Attack Complexity High
    Scope Changed
    Confidentiality High

    Threat Intelligence

    EPSS 0.24% (61st percentile)
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4.4 medium

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  • Snyk ID npm:cookie-signature:20160804
  • published 29 Aug 2016
  • disclosed 28 Jan 2014
  • credit tenbits

How to fix?

Upgrade to 1.0.4 or greater.


'cookie-signature' is a library for signing cookies.

Versions before 1.0.4 of the library use the built-in string comparison mechanism, ===, and not a time constant string comparison. As a result, the comparison will fail faster when the first characters in the token are incorrect. An attacker can use this difference to perform a timing attack, essentially allowing them to guess the secret one character at a time.

You can read more about timing attacks in Node.js on the Snyk blog: