adm-zip: Crafted ZIP file triggers 4GB memory allocation

Exploitation

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

CVSS

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

EPSS

• CVE-2026-39244: 0.84% estimated exploitation activity in the next 30 days; percentile 57.93 (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.

adm-zip before 0.5.18 is vulnerable to denial of service via a crafted ZIP file with a manipulated uncompressed size header field. In zipEntry.js line 103, Buffer.alloc(centralHeader.size) allocates memory based on the declared uncompressed size from the ZIP central directory header without validating it against the actual compressed data size or imposing any upper bound. The size value is read directly from the binary header at entryHeader.js line 266 with no bounds check. An attacker can craft a ~120-byte ZIP file that declares ~4GB uncompressed size, causing a memory allocation amplification ratio of over 33 million to 1. The allocation occurs before CRC validation, so the malicious payload cannot be rejected early. All extraction and read methods are affected: readFile(), readAsText(), extractEntryTo(), extractAllTo(), extractAllToAsync(), test(), and entry.getData(). Any application accepting untrusted ZIP files via adm-zip is vulnerable to immediate process crash.

Published by the source

10 Jul 2026, 18:32 UTC

Last modified by the source

10 Sep 2026, 03:51 UTC

Source last checked

26 Oct 2026, 12:57 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-xcpc-8h2w-3j85

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-xcpc-8h2w-3j85

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# Patch Next advisory brief: CVE-2026-39244

Advisory: adm-zip: Crafted ZIP file triggers 4GB memory allocation
IDs: CVE-2026-39244, GHSA-xcpc-8h2w-3j85
Record: https://patchnext.com/advisories/cve-2026-39244 (revision 2, source checked 26 Oct 2026, 12:57 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: adm-zip 0.6.0. A vendor fix does not mean a deployment is fixed.

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

## 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://osv.dev/vulnerability/GHSA-xcpc-8h2w-3j85 (OSV record GHSA-xcpc-8h2w-3j85 lists affected ranges: npm adm-zip >=0 <0.6.0 (fixed))
- Verified: https://github.com/advisories/GHSA-xcpc-8h2w-3j85 (GitHub-reviewed advisory GHSA-xcpc-8h2w-3j85 lists affected ranges: npm adm-zip >=0 <0.6.0)

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