Vulnerability · Published Nov 3, 2026 · Assigned by GitHub_M

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

Medium 6.1

In plain English

A medium-severity path traversal in zt-zip from zeroturnaround. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 15% of all known vulnerabilities).

Severity (CVSS 3.1)6.1Medium

Exploit odds (30 days)0.2%top 84.6% of all CVEs

Exploited in the wildNo reportsnot in CISA KEV

Attack toolingNoneno public tooling known

Official description

zt-zip is a Java library that provides convenience methods for ZIP archive manipulation. Prior to 1.18.0, the Zips.get(zip).unpack().destination(outputDir).process() fluent API in src/main/java/org/zeroturnaround/zip/Zips.java constructs output files directly from ZIP entry names without applying the destination-boundary validation used by ZipUtil.unpack(...). A crafted entry containing parent-directory traversal can therefore write outside outputDir through both the normal copy branch and the ZipEntryTransformer branch. Applications that extract untrusted archives only through ZipUtil.unpack(...) are unaffected because that API already calls checkDestinationFileForTraversal. This issue is fixed in version 1.18.0.

Affected products (as reported)

Vendor	Product	Versions
zeroturnaround	zt-zip	< 1.18.0

Weakness: CWE-22 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:L

References

https://github.com/zeroturnaround/zt-zip/security/advisories/GHSA-52c6-99qm-3hqr x_refsource_CONFIRM
https://github.com/zeroturnaround/zt-zip/pull/180 x_refsource_MISC
https://github.com/zeroturnaround/zt-zip/commit/59a76ad576b0fcd50ea018e3608afb946c1492fd x_refsource_MISC
https://github.com/zeroturnaround/zt-zip/releases/tag/v1.18.0 x_refsource_MISC