CVE-2021-21251 Explained : Impact and Mitigation

OneDev is an all-in-one devops platform with a critical 'zip slip' vulnerability in versions before 4.0.3. This vulnerability could lead to arbitrary file write when untarring user-controlled data.

Understanding CVE-2021-21251

This CVE refers to the 'ZipSlip Arbitrary File Upload' vulnerability affecting OneDev versions prior to 4.0.3.

What is CVE-2021-21251?

OneDev, a comprehensive devops platform, is susceptible to a 'zip slip' vulnerability before version 4.0.3. Attackers could exploit this flaw to overwrite existing files during the untar process.

The Impact of CVE-2021-21251

With a CVSS base score of 7.7 (High Severity), this vulnerability can allow malicious actors to perform arbitrary file writes, compromising the integrity of affected systems while requiring a low level of privileges for exploitation.

Technical Details of CVE-2021-21251

In OneDev versions earlier than 4.0.3, during the untar process of user-controlled data, there was a lack of checks to prevent files from traversing the file system and replacing existing files.

Vulnerability Description

The vulnerability arises due to the inadequate validation of paths in the tar archive, enabling extracted files to exist outside the specified folder, thus leading to potential file overwrites.

Affected Systems and Versions

OneDev versions less than 4.0.3 are impacted by this vulnerability.

Exploitation Mechanism

Exploiting this vulnerability requires a valid 'JobToken' and knowledge of other reported vulnerabilities, making successful exploitation more challenging.

Mitigation and Prevention

To mitigate the risks associated with CVE-2021-21251, immediate action is needed.

Immediate Steps to Take

Organizations should update their OneDev installations to version 4.0.3 or later to address this vulnerability effectively.

Long-Term Security Practices

Regularly monitor security advisories and promptly apply patches and updates to safeguard against known vulnerabilities.

Patching and Updates

Developers must prioritize security best practices and implement a robust patch management strategy to protect systems from potential threats.