Vulnerability · Published Sep 3, 2026 · Assigned by VulnCheck
CVE-2026-85396rubyzip before 3.4.0 Path Traversal in Zip::Entry#extract via Sibling-Directory Prefix
High 7.5
In plain English
A high-severity path traversal in rubyzip from rubyzip. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 47% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | ruby-zip | no fix listed | DEBIAN-CVE-2026-85396 |
| Debian:13 | ruby-zip | no fix listed | DEBIAN-CVE-2026-85396 |
| Debian:14 | ruby-zip | 3.4.0+dfsg-1 | DEBIAN-CVE-2026-85396 |
| RubyGems | rubyzip | 3.4.0 | GHSA-47m2-wp7j-p9vc |
| Ubuntu:22.04:LTS | ruby-zip | no fix listed | UBUNTU-CVE-2026-85396 |
| Ubuntu:24.04:LTS | ruby-zip | no fix listed | UBUNTU-CVE-2026-85396 |
| Ubuntu:26.04:LTS | ruby-zip | no fix listed | UBUNTU-CVE-2026-85396 |
Affected products (as reported)
Weakness: CWE-22 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
References
- Patch Commit patch
- https://github.com/rubyzip/rubyzip product
- rubyzip v3.4.0 Release Notes release-notes
- https://github.com/rubyzip/rubyzip/blob/v3.3.1/lib/zip/entry.rb technical-description
- https://github.com/geo-chen/oss/blob/main/rubyzip.md technical-description
- VulnCheck Advisory: rubyzip before 3.4.0 Path Traversal in Zip::Entry#extract via Sibling-Directory Prefix third-party-advisory