# CVE-2026-39244: adm-zip: Crafted ZIP file triggers 4GB memory allocation

> Attackers can crash applications using adm-zip by submitting small ZIP files with manipulated headers that trigger excessive memory allocation.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Jul 2026
- **Updated:** 10 Jul 2026
- **Also known as:** CLEANSTART-2026-CE47841, CLEANSTART-2026-OC57754, CLEANSTART-2026-ZL52542, CLSA-2026-1784856024, CLSA-2026-1790161376, CLSA-2026-1790162696, CLSA-2026-1790165044, CLSA-2026-1790176614, CLSA-2026-1791315520, ECHO-74cc-31c3-74b6, GHSA-xcpc-8h2w-3j85, MINI-38pj-8hm8-fr2m, MINI-38w2-jf2p-mrrj, MINI-4vf4-825c-crmj, MINI-5vw4-qw26-2fjw, MINI-7h3c-6prh-qjmr, MINI-9qcf-g6cf-mq73, MINI-c44m-6g72-cwj9, MINI-f388-cr6r-78pw, MINI-f6fw-58c9-6gfq, MINI-j56j-7v5h-7x7w, MINI-mrm7-fqpr-ff4c, MINI-p897-85xr-ccr5, MINI-rq38-phv8-j899, MINI-w6pm-4wcg-jwh7, ROOT-APP-NPM-CVE-2026-39244

## What is CVE-2026-39244?

CVE-2026-39244 is a high-severity denial of service vulnerability in n/a, published on 10 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2026-39244?

2 open source packages ship an affected version, including adm-zip.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `adm-zip` | npm | All versions | 0.6.0 |
| `adm-zip` | npm | All versions | 0.6.0 |

## How do I fix CVE-2026-39244?

Upgrade adm-zip to 0.6.0 or later.

## Is CVE-2026-39244 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-39244 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-39244 and fix it if it is affected.

What it is: CVE-2026-39244 is a high-severity denial of service vulnerability in n/a, published on 10 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-39244 exists.

Affected packages and fixed versions:
- adm-zip (npm): affected all versions; fixed in 0.6.0
- adm-zip (npm): affected all versions; fixed in 0.6.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-39244/ (Markdown: https://insights.sbomify.com/CVE-2026-39244/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-39244
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-39244
- OSV: https://osv.dev/vulnerability/CVE-2026-39244

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-39244/
Summaries are generated and may contain mistakes; the official description above is the record.