Arbitrary File Write via Archive Extraction (Zip Slip) Affecting zip-local package, versions <0.3.5



    Attack Complexity Low
    Confidentiality High
    Integrity High
    Availability High

    Threat Intelligence

    EPSS 0.17% (54th percentile)
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9.8 critical

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  • Snyk ID SNYK-JS-ZIPLOCAL-2327477
  • published 25 Jan 2022
  • disclosed 29 Dec 2021
  • credit 7he6uzzer

How to fix?

Upgrade zip-local to version 0.3.5 or higher.


zip-local is a to zip and unzip local directories

Affected versions of this package are vulnerable to Arbitrary File Write via Archive Extraction (Zip Slip) which can lead to an extraction of a crafted file outside the intended extraction directory.


var zipper = require('zip-local');

zipper.unzip("", function(error, unzipped) {

if(!error) {
// extract to the current working directory, function() { });

var unzippedfs = unzipped.memory();


Execute the following commands

1. npm install zip-local # Install affected module
2. zipslip example file can be found at -
3. node poc.js # Run the PoC


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