zt-zip: Path traversal in fluent API unpack

Exploitation

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

CVSS

8.2 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L

EPSS

• CVE-2026-63436: 0.24% estimated exploitation activity in the next 30 days; percentile 15.40 (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 `ZipUtil.unpack(...)` rejects ZIP entries that escape the target output directory, but the `Zips` fluent API appears to use a separate unpack implementation that does not apply the same destination-boundary check. A ZIP entry such as: ```text ../escape/poc.txt ``` is written outside the configured destination directory when processed with: ```java Zips.get(zip).unpack().destination(outputDir).process(); ``` The transformer branch is affected as well.

Tested Version commit: 067935dca375500d3ff025aafcdf0e4283931b1a

Root Cause In `src/main/java/org/zeroturnaround/zip/Zips.java`, `Zips.UnpackingCallback.process(...)` builds the output file directly from the ZIP entry name: ```java String entryName = zipEntry.getName(); File file = new File(destination, entryName); ``` The method then creates directories/files and copies content to that path: ```java FileUtils.forceMkdir(file.getParentFile()); file.createNewFile(); FileUtils.copy(in, file); ``` When a transformer is…

Published by the source

9 Nov 2026, 18:47 UTC

Last modified by the source

9 Nov 2026, 19:15 UTC

Source last checked

10 Nov 2026, 06:45 UTC

1. Revision 2 · amended · 10 Nov 2026

   Amended from osv record GHSA-52c6-99qm-3hqr

2. Revision 1 · created · 9 Nov 2026

   Published from ghsa record GHSA-52c6-99qm-3hqr

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# Patch Next advisory brief: CVE-2026-63436

Advisory: zt-zip: Path traversal in fluent API unpack
IDs: CVE-2026-63436, GHSA-52c6-99qm-3hqr
Record: https://patchnext.com/advisories/cve-2026-63436 (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: High (CVSS 8.2)
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 1.18.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven org.zeroturnaround:zt-zip: affected < 1.18.0; fixed in 1.18.0

## 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-52c6-99qm-3hqr (GitHub-reviewed advisory GHSA-52c6-99qm-3hqr lists affected ranges: Maven org.zeroturnaround:zt-zip >=0 <1.18.0)
- Verified: https://osv.dev/vulnerability/GHSA-52c6-99qm-3hqr (OSV record GHSA-52c6-99qm-3hqr lists affected ranges: Maven org.zeroturnaround:zt-zip >=0 <1.18.0 (fixed))

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