zt-zip: ZipUtil.unpack can change file permissions of output directory

Exploitation

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

CVSS 4.0

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

EPSS

• CVE-2026-63499: 0.28% estimated exploitation activity in the next 30 days; percentile 20.72 (FIRST EPSS, 2026-11-10). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary When using one of the `ZipUtil.unpack` overloads, the file permissions of the output directory can be changed. For example, when the output directory was only accessible to the 'owner' it could be instead made accessible to every OS user.

Details When the name of a ZIP entry resolves to the output directory itself (e.g. the name `/`), the path traversal checks permit it and then perform actions on that directory, such as applying the file permissions of the ZIP entry to it.

PoC This proof of concept requires an OS with support for POSIX file permissions. This issue itself is however not limited to those OS' with POSIX file permissions, see zt-zip's `ZTFilePermissionsUtil.fetchDefaultStrategy` which uses a fallback in that case. ```java // Uses Apache Commons Compress to create the malicious ZIP file // The issue itself is however in how zt-zip processes that ZIP file import org.apache.commons.compress.archivers.zip.AsiExtraField; import…

Published by the source

9 Nov 2026, 21:03 UTC

Last modified by the source

9 Nov 2026, 21:15 UTC

Source last checked

10 Nov 2026, 06:45 UTC

1. Revision 2 · amended · 10 Nov 2026

   Amended from osv record GHSA-v2g6-7r9j-v6px

2. Revision 1 · created · 9 Nov 2026

   Published from ghsa record GHSA-v2g6-7r9j-v6px

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# Patch Next advisory brief: CVE-2026-63499

Advisory: zt-zip: ZipUtil.unpack can change file permissions of output directory
IDs: CVE-2026-63499, GHSA-v2g6-7r9j-v6px
Record: https://patchnext.com/advisories/cve-2026-63499 (revision 2, source checked 10 Nov 2026, 06:45 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: org.zeroturnaround:zt-zip 1.18.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven org.zeroturnaround:zt-zip: affected < 1.18.1; fixed in 1.18.1

## Suggested inspection (read-only)
- Maven org.zeroturnaround:zt-zip: 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 org.zeroturnaround:zt-zip.
- 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://github.com/advisories/GHSA-v2g6-7r9j-v6px (GitHub-reviewed advisory GHSA-v2g6-7r9j-v6px lists affected ranges: Maven org.zeroturnaround:zt-zip >=0 <=1.18.0)
- Verified: https://osv.dev/vulnerability/GHSA-v2g6-7r9j-v6px (OSV record GHSA-v2g6-7r9j-v6px lists affected ranges: Maven org.zeroturnaround:zt-zip >=0 <1.18.1 (fixed))

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