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VulnerabilityPublished

CVE-2026-63436: zt-zip · Path traversal in fluent API unpack

Affects org.zeroturnaround:zt-zipSource GCVE Database

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Authoritative record:CVE-2026-63436· Medium 6.1

Not known to be exploited · CVSS 6.1 Medium : upgrade to 1.18.0 when convenient.

Data as of 9 Nov 2026, 19:20 UTC

CVSS 3.1 base score
6.1Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (GitHub_M)CVSS 3.16.1
Patch
Available – fixed in 1.18.0
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:L

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 3 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 9 Nov 2026.

What to do

Upgrade org.zeroturnaround:zt-zip to 1.18.0.

Affected software

ProductAffectedFixed in
Mavenorg.zeroturnaround:zt-zipAffected
  • <1.18.0
Fixed in
  • 1.18.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix is available in version 1.18.0 of org.zeroturnaround:zt-zip. Users should upgrade to this version or later to ensure the destination-boundary validation is applied and prevent path traversal during ZIP extraction. The vendor advisory confirms the patch and recommends applying the same canonical path checks used by ZipUtil.unpack(...) before any filesystem write in the Zips fluent API unpack process.

Description

A path traversal vulnerability exists in the org.zeroturnaround:zt-zip library's fluent API unpack method (CVE-2026-63436). The Zips fluent API does not properly validate ZIP entry paths, allowing entries with '../' sequences to write files outside the intended extraction directory. This can lead to arbitrary file writes outside the target directory when unpacking attacker-controlled ZIP files. The issue affects versions prior to 1.18.0 and is fixed in version 1.18.0.

References

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