CVE-2026-85396

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

CVE-2026-85396 is fixed in ruby-zip on 1 platform by DEBIAN-CVE-2026-85396 (version 3.4.0+dfsg-1), released September 4, 2026. It is not reported as exploited. Patch Radar priority: High.

High

CVSS

7.5

Important

Exploitation

None reported

No vendor assessment

CISA KEV

Not listed

Not in the Known Exploited Vulnerabilities catalog

EPSS

0.0056

47th percentile

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.

Where it's fixed

Product	Fixed in	Fix	Released
Linux
ruby-zip · Debian 14	3.4.0+dfsg-1	DEBIAN-CVE-2026-85396	Sep 4, 2026

Details

Published
September 3, 2026
Weakness
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Vendor advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-85396

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