rubyzip path traversal vulnerability

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

8.7 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-85396: 0.56% estimated exploitation activity in the next 30 days; percentile 46.95 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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 ../uploadbackup/owned.sh to write files outside the intended extraction directory into sibling paths sharing the destination prefix.

Published by the source

3 Sep 2026, 21:31 UTC

Last modified by the source

25 Sep 2026, 19:45 UTC

Source last checked

26 Oct 2026, 15:52 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-47m2-wp7j-p9vc

2. Revision 2 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-47m2-wp7j-p9vc

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# Patch Next advisory brief: CVE-2026-85396

Advisory: rubyzip path traversal vulnerability
IDs: CVE-2026-85396, GHSA-47m2-wp7j-p9vc
Record: https://patchnext.com/advisories/cve-2026-85396 (revision 3, source checked 26 Oct 2026, 15:52 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: rubyzip 3.4.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- RubyGems rubyzip: affected < 3.4.0; fixed in 3.4.0

## Suggested inspection (read-only)
- RubyGems rubyzip: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on rubyzip.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-47m2-wp7j-p9vc (OSV record GHSA-47m2-wp7j-p9vc lists affected ranges: RubyGems rubyzip >=0 <3.4.0 (fixed))
- Verified: https://github.com/advisories/GHSA-47m2-wp7j-p9vc (GitHub-reviewed advisory GHSA-47m2-wp7j-p9vc lists affected ranges: RubyGems rubyzip >=0 <3.4.0)

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