CVE-2019-3902 : Vulnerability Insights and Analysis

A vulnerability has been discovered in versions of Mercurial prior to 4.9. An exploit involving the usage of symbolic links and subrepositories allowed malicious actors to bypass Mercurial's path-checking mechanism, permitting them to create files in locations outside of a repository's scope.

Understanding CVE-2019-3902

This CVE affects the Mercurial version before 4.9 and poses a medium severity risk with a CVSS base score of 5.1.

What is CVE-2019-3902?

The vulnerability in Mercurial before version 4.9 allows attackers to write files outside the repository's boundaries using symbolic links and subrepositories.

The Impact of CVE-2019-3902

Attack Complexity: High
Attack Vector: Local
Integrity Impact: High
Base Score: 5.1 (Medium Severity)

Technical Details of CVE-2019-3902

This section provides detailed technical information about the CVE.

Vulnerability Description

The flaw in Mercurial before 4.9 enables the circumvention of path-checking logic, leading to unauthorized file writing outside the repository.

Affected Systems and Versions

Product: Mercurial
Vendor: The Mercurial Project
Versions Affected: Before 4.9

Exploitation Mechanism

Malicious actors exploit symbolic links and subrepositories to create files beyond the repository's intended scope.

Mitigation and Prevention

Protect your systems from CVE-2019-3902 with the following steps:

Immediate Steps to Take

Update Mercurial to version 4.9 or newer to mitigate the vulnerability.
Regularly monitor and restrict the usage of symbolic links and subrepositories within Mercurial.

Long-Term Security Practices

Implement strict file system permissions to prevent unauthorized file writes.
Conduct regular security audits to identify and address potential vulnerabilities.

Patching and Updates

Stay informed about security updates and patches released by Mercurial to address known vulnerabilities.