Arbitrary File Write via Archive Extraction (Zip Slip) Affecting adm-zip package, versions <0.4.11



    Attack Complexity Low
    Integrity High
    Availability High

    Threat Intelligence

    Exploit Maturity Mature
    EPSS 0.09% (37th percentile)
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5.5 medium

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  • Snyk ID npm:adm-zip:20180415
  • published 31 May 2018
  • disclosed 14 Apr 2018
  • credit Snyk Security Research, Sébastien Mignot, Alex Chapman

How to fix?

Upgrade adm-zip to version 0.4.11 or higher.


adm-zip is a JavaScript implementation for zip data compression for NodeJS.

Affected versions of this package are vulnerable to Arbitrary File Write via Archive Extraction (Zip Slip).


It is exploited using a specially crafted zip archive, that holds path traversal filenames. When exploited, a filename in a malicious archive is concatenated to the target extraction directory, which results in the final path ending up outside of the target folder. For instance, a zip may hold a file with a "../../file.exe" location and thus break out of the target folder. If an executable or a configuration file is overwritten with a file containing malicious code, the problem can turn into an arbitrary code execution issue quite easily.

The following is an example of a zip archive with one benign file and one malicious file. Extracting the malicous file will result in traversing out of the target folder, ending up in /root/.ssh/ overwriting the authorized_keys file:

+2018-04-15 22:04:29 ..... 19 19 good.txt

+2018-04-15 22:04:42 ..... 20 20 ../../../../../../root/.ssh/authorized_keys