cthackers adm-zip up to 0.5.18 ZIP file zipEntry.js size allocation of resources

Summaryinfo

A vulnerability was found in cthackers adm-zip up to 0.5.18 and classified as problematic. Affected by this vulnerability is the function readFile/readAsText/extractEntryTo/extractAllTo/extractAllToAsync/test/entry.getData of the file zipEntry.js of the component ZIP file Handler. Executing a manipulation of the argument size can lead to allocation of resources. This vulnerability is tracked as CVE-2026-39244. The attack can be launched remotely. No exploit exists.

Detailsinfo

A vulnerability classified as problematic was found in cthackers adm-zip up to 0.5.18. This vulnerability affects the function readFile/readAsText/extractEntryTo/extractAllTo/extractAllToAsync/test/entry.getData of the file zipEntry.js of the component ZIP file Handler. The manipulation of the argument size with an unknown input leads to a allocation of resources vulnerability. The CWE definition for the vulnerability is CWE-770. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor. As an impact it is known to affect availability. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability was named CVE-2026-39244 since 04/06/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Successful exploitation requires user interaction by the victim. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1499 by the MITRE ATT&CK project.

Upgrading to version 0.5.18 eliminates this vulnerability.

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Productinfo

Vendor

• cthackers

Name

• adm-zip

Version

• 0.5.0
• 0.5.1
• 0.5.2
• 0.5.3
• 0.5.4
• 0.5.5
• 0.5.6
• 0.5.7
• 0.5.8
• 0.5.9
• 0.5.10
• 0.5.11
• 0.5.12
• 0.5.13
• 0.5.14
• 0.5.15
• 0.5.16
• 0.5.17
• 0.5.18

CPE 2.3info

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CPE 2.2info

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Entryinfo

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