Lodash versions 4.0.0 through 4.17.22 are vulnerable to prototype pollution in the _.unset and _.omit functions. This vulnerability allows attackers to pass crafted paths, which can lead to the deletion of methods from global prototypes. However, while the issue permits deletion of properties, it does not allow for overwriting their original behavior. This is a significant concern as it can affect the integrity of the application's functionality.
The vulnerability has been assigned a CVSS score of 6.9, classifying it as medium severity. This score indicates that while the vulnerability is not critical, it still poses risks to organizations that use affected versions of Lodash. Attackers may leverage this flaw to manipulate the prototype of global objects in unexpected ways, potentially leading to broader impacts within an application.
Organizations should prioritize patching immediately. The issue has been addressed in Lodash version 4.17.23, which eliminates the vulnerability. It is crucial for teams using Lodash to audit their dependencies and ensure they are running the latest version to safeguard against potential exploitation.
As of now, there is a known exploit for this vulnerability. However, it is not classified as high-profile, thus organizations should remain vigilant but may not need to act as urgently as they would for more publicized vulnerabilities.
In conclusion, all organizations using Lodash versions prior to 4.17.23 should take immediate action to remediate this vulnerability. Regular updates and security audits can help mitigate risks and protect against potential threats.
Vulnerability Details
The vulnerability allows for prototype pollution in the Lodash library through the _.unset and _.omit functions. This is a medium severity vulnerability due to its capability to delete properties from global prototypes, which can lead to unexpected behavior in applications that rely on Lodash.
The CVSS score of 6.9 indicates a medium severity classification, making it essential for organizations to assess their risk exposure and take appropriate remediation steps. The affected products include all versions of Lodash prior to 4.17.23. The issue was disclosed on January 21, 2026.
CWE classification for this vulnerability is CWE-1321, which relates to improper handling of prototype pollution.
Technical Analysis
The root cause of this vulnerability lies in the way Lodash handles paths in the _.unset and _.omit functions. Attackers can craft specific input paths that allow them to manipulate the prototype chain, leading to the deletion of critical methods from global objects.
The attack vector for this vulnerability is network-based, meaning that an attacker does not need physical access to the system to exploit the vulnerability. The attack complexity is low, requiring no special privileges or user interaction, which increases the potential for exploitation.
In terms of impacts, the vulnerability has low integrity and availability impacts, but the confidentiality impact is none. However, the potential for attackers to delete important properties from the prototype chain could lead to broader integrity issues within applications using Lodash.
Risk & Impact Analysis
Risk to organizations includes the potential for application instability and unexpected behavior due to method deletions from global prototypes. This vulnerability can be particularly harmful in environments where Lodash is widely used, as it can lead to a chain reaction of failures across multiple components.
The blast radius of this vulnerability is significant, as it affects all instances of Lodash in applications that utilize its functions. Given the popularity of Lodash, the urgency for organizations to address this vulnerability is moderate. Organizations should schedule remediation to ensure their applications are secure.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | Yes |
Public PoC | Yes |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
All versions of Lodash from 4.0.0 to 4.17.22 are affected. Users should upgrade to Lodash version 4.17.23 or later to mitigate this vulnerability.
Mitigation & Remediation
To mitigate this vulnerability, organizations should update Lodash to version 4.17.23 or later. Regular audits of dependencies and applying security patches promptly is crucial in maintaining secure applications.
In cases where immediate patching is not feasible, organizations should consider implementing configuration hardening strategies to limit the impact of this vulnerability. Network controls and monitoring can also help to detect any unusual behavior that may indicate exploitation attempts.
For more comprehensive guidance on application security, organizations may refer to the application security assessment services.
Detection Guidance
Organizations should monitor for log indicators related to Lodash functions, specifically the _.unset and _.omit functions. Any unusual patterns or behavioral anomalies could indicate attempts to exploit this vulnerability.
Network signatures can also be established to detect potential exploitation attempts, while system changes should be closely monitored for any unauthorized modifications to global prototypes.
AppSecure Threat Intelligence Insight
The long-term significance of this vulnerability lies in its representation of broader issues related to prototype pollution vulnerabilities in JavaScript libraries. Security teams should recognize the potential for similar vulnerabilities in other libraries and implement strict coding standards to prevent such issues.
This vulnerability highlights the importance of regular dependency audits and staying updated with the latest security patches. Organizations must prioritize security in their development processes to mitigate risks associated with third-party libraries.
For further reading on secure coding practices, organizations can consult the secure coding practices guide and consider engaging in penetration testing to identify similar weaknesses across their applications.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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