CVE-2026-39245

Description

decompress before 4.2.2 contains an improper path containment check that enables directory traversal and arbitrary file write. The safeMakeDir function (index.js line 29) and the extraction path validation (index.js line 106) use String.indexOf() to verify the resolved path is within the output directory: realDestinationDir.indexOf(realOutputPath) !== 0. This check is flawed because it does not enforce a path separator boundary. For example, "/tmp/app_config".indexOf("/tmp/app") returns 0, incorrectly passing the check even though /tmp/app_config is outside /tmp/app. Combined with the unvalidated symlink creation in the same package, an attacker can write arbitrary files to directories adjacent to the extraction target. This is a bypass of the fix for CVE-2020-12265. The correct check requires appending a path separator: realParentPath.indexOf(realOutputPath + path.sep) !== 0.

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Produits concernés

• Decompress project decompress

Scores CVSS

Faiblesses (CWE)

• CWE-22

Références

• https://github.com/kevva/decompress Product
• https://github.com/kevva/decompress/issues/115 ExploitVendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2020-12265 US Government Resource
• https://www.npmjs.com/package/decompress Product
• https://github.com/kevva/decompress/issues/115 ExploitVendor Advisory

Ailleurs

• NVD
• CVE.org
• CIRCL Vulnerability-Lookup
• CERT-FR
• GitHub Advisories