Arbitrary file write via sibling-prefix path check
Published Sep 3, 2026 · Updated Sep 3, 2026
Path traversal in Rubyzip before 3.4.0 allows remote attackers to write files outside an extraction directory through crafted ZIP entries. Zip::Entry#extract resolves an entry path, then accepts it when its absolute string merely starts with the destination string, without requiring a trailing directory separator. An application must extract an attacker-controlled archive; a sibling path sharing the destination prefix can then receive attacker-supplied files.
Summary
What happened
Path traversal in Rubyzip before 3.4.0 allows remote attackers to write files outside an extraction directory through crafted ZIP entries. Zip::Entry#extract resolves an entry path, then accepts it when its absolute string merely starts with the destination string, without requiring a trailing directory separator. An application must extract an attacker-controlled archive; a sibling path sharing the destination prefix can then receive attacker-supplied files.
The record
- CVE
- CVE-2026-85396
- Published
- Sep 3, 2026
- Updated
- Sep 3, 2026
- Vendor
- Rubyzip
- Product
- Rubyzip
- Classifications
- CWE-22
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 3, 2026CVE publishedPublication date reported by the CVE source.
- Sep 3, 2026Record updatedLatest update available in the CVE record.
Exploitability
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Is a vulnerable build present?
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- Affected versionversion=0 <3.4.0
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What is affected?
Published CVSS scores
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Attacks
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Technologies
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