Arbitrary File Write via Archive Extraction (Zip Slip) Affecting unzipper package, versions *
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-JS-UNZIPPER-18365659
- published28 Jul 2026
- disclosed27 Jul 2026
- creditAbdul Moiz
Introduced: 27 Jul 2026
NewCVE-2026-17514 (opens in a new tab)How to fix?
There is no fixed version for unzipper.
Overview
unzipper is a library for the Uzip cross-platform streaming AP.I
Affected versions of this package are vulnerable to Arbitrary File Write via Archive Extraction (Zip Slip) in the extraction path validation in lib/extract.js and lib/Open/directory.js, which check only that the resolved path begins with the destination string (extractPath.indexOf(opts.path) != 0) without enforcing a directory-separator boundary. An attacker can write files outside the intended extraction directory, enabling file overwrite or code execution, by supplying a ZIP archive whose entry resolves to a sibling path such as /tmp/dest-evil/escaped.txt that shares the destination's string prefix, which a victim then extracts. Exploitation requires the victim to extract an untrusted archive with unzipper, and it works through sibling-prefix paths since standard ../../ traversal remains blocked.
Note: This is a bypass of the fix for the vulnerability described in CVE-2018-1002203.
Details
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