What’s Vulnerable › Vulnerabilities

CVE-2026-85396: rubyzip before 3.4.0 Path Traversal in Zip::Entry#extract via Sibling-Directory Prefix

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-03 · updated 2026-09-24
• Weakness: CWE-22

Description

rubyzip versions before 3.4.0 contain a path traversal vulnerability in Zip::Entry#extract that fails to properly validate extraction paths using prefix comparison without trailing separators. Attackers can craft archive entries with names like ../upload_backup/owned.sh to write files outside the intended extraction directory into sibling paths sharing the destination prefix.

Affected products

• rubyzip: before 3.4.0 — fixed in 3.4.0

How to fix

Upgrade to a fixed version: rubyzip 3.4.0. Check the vendor advisory for mitigations.

References

• https://github.com/geo-chen/oss/blob/main/rubyzip.md
• https://github.com/rubyzip/rubyzip
• https://github.com/rubyzip/rubyzip/blob/v3.3.1/lib/zip/entry.rb
• https://github.com/rubyzip/rubyzip/commit/17edfbf4423b83211b075acc23a7d8640da63449
• https://github.com/rubyzip/rubyzip/releases/tag/v3.4.0
• https://www.vulncheck.com/advisories/rubyzip-before-3.4.0-path-traversal-in-zip-entry-extract-via-sibling-directory-prefix

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