CVE-2026-114103 in adm-zip
Summary
by MITRE • 10/22/2026
adm-zip 0.6.0 contains a decompression bomb protection bypass that allows attackers to evade the maxOutputLength guard by targeting the asynchronous getDataAsync() path in methods/inflater.js. Attackers can craft ZIP entries with falsified small declared sizes and high-ratio DEFLATE payloads to exhaust memory in applications reading entries asynchronously.
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Analysis
by VulDB Data Team • 10/22/2026
The vulnerability identified in adm-zip version 0.6.0 represents a critical failure in input validation logic, specifically within the asynchronous data retrieval pathway of the library's decompression engine. This flaw allows an attacker to bypass security controls designed to prevent resource exhaustion attacks by exploiting inconsistencies between declared metadata and actual payload characteristics. The core issue resides in methods/inflater.js, where the getDataAsync function fails to enforce strict size constraints during the streaming or asynchronous extraction process. Unlike synchronous operations that may have more robust checks against total output length, this specific code path lacks adequate safeguards to verify that the decompressed data does not exceed a predefined maximum limit before it is fully materialized in memory.
This technical flaw enables what is commonly known as a decompression bomb attack, also referred to as a zip-bomb or archive bomb. In such an scenario, an attacker crafts a malicious ZIP file containing entries with artificially small declared uncompressed sizes but utilizes high-ratio DEFLATE compression algorithms for the payload data. When the application processes these entries using the vulnerable asynchronous method, it allocates memory based on the misleadingly small size information provided in the archive header rather than monitoring the actual expansion ratio during decompression. As a result, the library attempts to store vastly larger amounts of data into memory buffers than anticipated by the system's resource limits or configuration settings.
The operational impact of this vulnerability is severe, primarily manifesting as a Denial of Service condition through excessive memory consumption. Applications relying on adm-zip for processing user-uploaded archives can experience rapid heap exhaustion when handling these crafted payloads. This leads to application crashes, unresponsiveness, and potential instability in the underlying server environment. In cloud-native or containerized deployments, such resource exhaustion can trigger automatic restarts of containers due to memory limits being exceeded, causing service disruption for legitimate users. Furthermore, if the decompressed data is subsequently written to disk without proper size verification, it could lead to disk space exhaustion as well, compounding the denial-of-service effect across multiple system resources.
From a classification perspective, this vulnerability aligns with CWE-409, which describes Improper Handling of Highly Compressed Data (Data Amplification). It also relates closely to CWE-770, Allocation of Resources Without Limits or Throttling, as the application fails to restrict the amount of system resources consumed by untrusted input. In terms of offensive security frameworks, this exploit technique corresponds to MITRE ATT&CK T1496, Resource Hijacking, specifically under sub-techniques involving resource exhaustion via compression algorithms. The attack vector typically involves remote interaction where an attacker uploads or provides access to the malicious archive, making it a significant risk for web applications and services that accept file inputs without rigorous validation of their internal structure.
Mitigation strategies must focus on implementing robust input validation and enforcing strict limits on decompression ratios regardless of whether the operation is synchronous or asynchronous. Developers should ensure that all code paths within adm-zip, particularly those involving getDataAsync, validate the actual size of decompressed data against a configured maximum threshold before allocating memory buffers. Upgrading to patched versions of the library where this guard has been properly implemented across all execution paths is essential. Additionally, applications should employ sandboxing techniques such as running file processing in isolated containers with strict memory limits and using timeout mechanisms to abort long-running or resource-intensive decompression tasks. Regular security audits focusing on archive handling logic are recommended to identify similar bypasses in other libraries that may share this architectural weakness.