adm-zip: getDataAsync() bypasses the maxOutputLength size guard enforced by the synchronous getData() path

Exploitation

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

CVSS

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

EPSS

• CVE-2026-114103: 0.40% estimated exploitation activity in the next 30 days; percentile 34.69 (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 adm-zip enforces a maxOutputLength guard against decompression bombs on its synchronous getData() path, but the equivalent asynchronous getDataAsync() path does not enforce it — it accumulates and returns the entire decompressed output regardless of the entry's declared size. An application that checks an entry's declared size before deciding to process it, then reads the entry via getDataAsync() (a completely ordinary, often-recommended choice for I/O in Node.js), gets none of the protection it believes it has. Details - methods/inflater.js:3-10 passes {maxOutputLength: expectedLength} to inflateRawSync, which Node enforces. - methods/inflater.js:12-31 passes the same option to createInflateRaw but never enforces it on the streaming path — it just accumulates every chunk and allocates a final Buffer of whatever size resulted. PoC Impact An application that validates a declared size before reading an entry, then uses the async API, gets no protection against a high-ratio…

Published by the source

29 Sep 2026, 23:10 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-c6fg-446q-cg94

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-c6fg-446q-cg94

3. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-c6fg-446q-cg94

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# Patch Next advisory brief: CVE-2026-114103

Advisory: adm-zip: getDataAsync() bypasses the maxOutputLength size guard enforced by the synchronous getData() path
IDs: CVE-2026-114103, GHSA-c6fg-446q-cg94
Record: https://patchnext.com/advisories/ghsa-c6fg-446q-cg94 (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 5.3)
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-c6fg-446q-cg94 (GitHub-reviewed advisory GHSA-c6fg-446q-cg94 lists affected ranges: npm adm-zip >=0 <=0.6.0)
- Verified: https://osv.dev/vulnerability/GHSA-c6fg-446q-cg94 (OSV record GHSA-c6fg-446q-cg94 lists affected ranges: npm adm-zip >=0 <0.6.1 (fixed))

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