adm-zip: Duplicate ZIP entry names: getEntry() and extractAllTo() resolve to different content

Exploitation

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

CVSS

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

EPSS

• CVE-2026-114104: 0.33% estimated exploitation activity in the next 30 days; percentile 26.28 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary A ZIP file can contain two entries with the identical name. adm-zip keeps both in its internal entry list, but its name-lookup table only retains the last one written. getEntry(name) and extractAllTo() walk these two different internal structures, so they can each resolve a duplicate name to a different entry. An application that validates a named entry's contents via getEntry() before trusting an archive, then extracts the whole archive, can end up approving one file's content while a different file's bytes are what actually land on disk under that name. Details - zipFile.js:58-83 retains both entries in entryList but overwrites entryTable[name] with only the last one written. - adm-zip.js:83-95,658-663 uses entryTable for getEntry() lookups — returns the last duplicate. - adm-zip.js:769-914 iterates entryList for extraction — writes the first duplicate (sync, default overwrite policy). PoC Reproduced on the pinned commit (2b4d84087d45344643e0183756e19191d52815cc) Impact An…

Published by the source

29 Sep 2026, 23:11 UTC

Last modified by the source

21 Oct 2026, 10:57 UTC

Source last checked

26 Oct 2026, 13:06 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-p634-w6r4-rjp2

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-p634-w6r4-rjp2

3. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-p634-w6r4-rjp2

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# Patch Next advisory brief: CVE-2026-114104

Advisory: adm-zip: Duplicate ZIP entry names: getEntry() and extractAllTo() resolve to different content
IDs: CVE-2026-114104, GHSA-p634-w6r4-rjp2
Record: https://patchnext.com/advisories/ghsa-p634-w6r4-rjp2 (revision 3, source checked 26 Oct 2026, 13:06 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: adm-zip 0.6.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm adm-zip: affected <= 0.6.0; fixed in 0.6.1

## Suggested inspection (read-only)
- `npm ls adm-zip --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## 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 adm-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-p634-w6r4-rjp2 (GitHub-reviewed advisory GHSA-p634-w6r4-rjp2 lists affected ranges: npm adm-zip >=0 <=0.6.0)
- Verified: https://osv.dev/vulnerability/GHSA-p634-w6r4-rjp2 (OSV record GHSA-p634-w6r4-rjp2 lists affected ranges: npm adm-zip >=0 <0.6.1 (fixed))

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