CVE-2026-114104: adm-zip before 0.6.1 Duplicate ZIP Entry Name Validation Bypass

Severity: medium (CVSS 5.9 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-21 · updated 2026-10-28
Weakness: CWE-436

Description

adm-zip before 0.6.1 contains an inconsistent entry resolution vulnerability that allows attackers to bypass content validation by supplying ZIP archives with duplicate entry names. Attackers can craft archives where getEntry() returns the last duplicate while extractAllTo() writes the first, causing unvalidated bytes to be written to disk.

Affected products

cthackers adm-zip: before 0.6.1 — fixed in 0.6.1

How to fix

Upgrade to a fixed version: cthackers adm-zip 0.6.1. Check the vendor advisory for mitigations.

References

https://github.com/cthackers/adm-zip/security/advisories/GHSA-p634-w6r4-rjp2
https://www.vulncheck.com/advisories/adm-zip-before-0.6.1-duplicate-zip-entry-name-validation-bypass
https://github.com/cthackers/adm-zip/security/advisories/GHSA-p634-w6r4-rjp2

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