CVE-2026-25047 in deepHas
Summary
by MITRE • 01/30/2026
deepHas provides a test for the existence of a nested object key and optionally returns that key. A prototype pollution vulnerability exists in version 1.0.7 of the deephas npm package that allows an attacker to modify global object behavior. This issue was fixed in version 1.0.8.
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Analysis
by VulDB Data Team • 05/01/2026
The deepHas npm package vulnerability represents a critical prototype pollution flaw that emerged in version 1.0.7 and was subsequently addressed in version 1.0.8. This vulnerability stems from improper handling of object property access during nested key testing operations, creating a pathway for attackers to manipulate JavaScript prototype chains. The flaw specifically affects applications that utilize the deepHas library to test for the existence of nested object properties while simultaneously retrieving those values. When an attacker crafts malicious input containing specially formatted property paths, the library fails to properly sanitize these inputs before processing them against global object prototypes.
The technical implementation of this vulnerability aligns with CWE-471, which describes the improper handling of dynamically-controlled data structures. The deepHas package operates by traversing nested object structures to determine key existence, but during this traversal process, it fails to validate or sanitize the property names being accessed. This allows an attacker to inject property names that target prototype properties, effectively polluting the Object.prototype chain with malicious values. The vulnerability is particularly dangerous because it can be exploited through user-controllable input that gets processed by the deepHas library, making it a prime candidate for server-side prototype pollution attacks.
The operational impact of this vulnerability extends beyond simple data corruption, as prototype pollution can lead to severe consequences including remote code execution, denial of service, and privilege escalation attacks. When global prototype properties are modified, all objects that inherit from Object.prototype become vulnerable to the attacker's modifications, potentially affecting the entire application runtime environment. This vulnerability can be leveraged in conjunction with other attack vectors, particularly those targeting JavaScript engines or application logic that relies on prototype-based inheritance patterns. The attack surface is broad since deepHas is commonly used in server-side applications, API frameworks, and data processing pipelines where user input is frequently processed through nested object traversal operations.
Mitigation strategies for this prototype pollution vulnerability must address both immediate remediation and long-term architectural security considerations. The most direct solution involves upgrading to version 1.0.8 or later of the deepHas package, which implements proper input sanitization and prototype chain validation. Security teams should conduct comprehensive code audits to identify all instances where deepHas is used and verify that these usages are properly secured. Additionally, implementing input validation frameworks and using secure coding practices that prevent untrusted data from reaching prototype manipulation functions can significantly reduce the risk. Organizations should also consider implementing runtime protections such as prototype pollution detection mechanisms and monitoring for unusual prototype modifications, as outlined in the attack patterns documented under the MITRE ATT&CK framework for prototype pollution techniques. The vulnerability demonstrates the importance of proper input validation in JavaScript applications and highlights the need for security-conscious dependency management practices.