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Fencer Vulns
high 7.5

CVE-2026-39244 json

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

published 2026-07-10 4 mo ago modified 2026-09-10 1 mo ago also GHSA-xcpc-8h2w-3j85 , EUVD-2026-42960

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.8%
EPSS 0.8% chance of exploitation in 30 days, percentile 58%
public exploits
0
none known

Summary

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.

Patch / fix

  • npm adm-zip 0.6.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-39244 updated cvss 6.5

adm-zip: adm-zip: Denial of Service via crafted ZIP file leading to excessive memory allocation

  • Red Hat Advanced Cluster Management for Kubernetes 2 rhacm2/volsync-rhel9, rhacm2/volsync-operator-bundle Red Hat Build of Podman Desktop rh-podman-desktop.git Red Hat Developer Hub 1 rhdh/rhdh-hub-rhel9 Red Hat Enterprise Linux 8 mozjs60, dotnet5.0-build-reference-packages Red Hat Enterprise Linux 9 gjs Red Hat OpenShift AI (RHOAI) rhoai/odh-mlflow-rhel9, rhoai/odh-dashboard-rhel9, rhoai/odh-mod-arch-maas-rhel9, rhoai/odh-mod-arch-automl-rhel9, rhoai/odh-mod-arch-gen-ai-rhel9, rhoai/odh-mod-arch-mlflow-rhel9, +3 more
    +1 more products
    Red Hat Self-service automation portal 2 ansible-automation-platform/automation-portal
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Cluster Observability Operator 1.5 cluster-observability-operator/distributed-tracing-console-plugin-pf4-rhel9 1790854545, cluster-observability-operator/distributed-tracing-console-plugin-pf5-rhel9 1790854478, cluster-observability-operator/distributed-tracing-console-plugin-pf6-rhel9 1790854538
    fixed: vendor fix RHSA-2026:74609
  • Red Hat Cluster Observability Operator 1.5 cluster-observability-operator/perses-rhel9 1790854501, cluster-observability-operator/thanos-rhel9 1790854526, cluster-observability-operator/korrel8r-rhel9 1790854490, cluster-observability-operator/prometheus-rhel9 1790857922, cluster-observability-operator/alertmanager-rhel9 1790854499, cluster-observability-operator/perses-rhel9-operator 1790854601, +16 more
    not affected: vulnerable code not present
  • Red Hat OpenShift Container Platform 4 openshift4/ose-console, openshift4/ose-monitoring-plugin-rhel9 Red Hat OpenShift Container Platform 5 openshift5/ose-monitoring-plugin-rhel9
    not affected: vulnerable code not in execute path

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
4 mo ago

Exploit prediction

0.84% chance of exploitation in the next 30 days, higher than 58% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/cthackers/adm-zip/issues/568 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
npm adm-zip
<0.6.0
0.6.0

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption
  • CWE-789 Memory Allocation with Excessive Size Value

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.