Arbitrary File Write via Archive Extraction (Zip Slip) Affecting package, versions <1.0.0

  • Exploit Maturity

    Proof of concept

  • Attack Complexity


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  • snyk-id


  • published

    5 Mar 2020

  • disclosed

    5 Mar 2020

  • credit

    Sam Sanoop of Snyk Security Team

Introduced: 5 Mar 2020

CWE-29 Open this link in a new tab
First added by Snyk

How to fix?

Upgrade to version 1.0.0 or higher.

Overview is a package go-unzip provides a very simple library to extract zip archive

Affected versions of this package are vulnerable to Arbitrary File Write via Archive Extraction (Zip Slip). ZIP Path traversal is possible during extraction due to no validation and sanitization of filenames.


package main
import (""

func main() { u := unzip.New("/home/snoopy/", "/home/snoopy/uploads") err := u.Extract() if err != nil { fmt.Println(err) } }


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