CVE-2019-3858 : Security Advisory and Response

A vulnerability in libssh2 versions prior to 1.8.1 allows unauthorized access when a specific SFTP packet is received, potentially leading to service disruption or information extraction.

Understanding CVE-2019-3858

An out of bounds read flaw in libssh2 before 1.8.1 can be exploited by a remote attacker compromising an SSH server.

What is CVE-2019-3858?

An unauthorized access vulnerability in libssh2 versions before 1.8.1
Occurs when a server receives a specific SFTP packet
Attackers gaining control over an SSH server can disrupt services or extract client memory data

The Impact of CVE-2019-3858

CVSS v3.0 Base Score: 5 (Medium Severity)
Attack Complexity: High
Attack Vector: Network
User Interaction: Required
Scope: Unchanged
Confidentiality, Integrity, and Availability Impact: Low

Technical Details of CVE-2019-3858

An overview of the technical aspects of the vulnerability.

Vulnerability Description

Out of bounds read flaw in libssh2 before 1.8.1
Triggered by a specially crafted SFTP packet
Allows a remote attacker to cause Denial of Service or read client memory

Affected Systems and Versions

Product: libssh2
Vendor: The libssh2 Project
Affected Version: 1.8.1

Exploitation Mechanism

Remote attacker compromising an SSH server
Crafting a malicious SFTP packet to trigger the vulnerability

Mitigation and Prevention

Best practices to mitigate the CVE-2019-3858 vulnerability.

Immediate Steps to Take

Update libssh2 to version 1.8.1 or later
Monitor for any unauthorized access attempts
Implement network segmentation to limit exposure

Long-Term Security Practices

Regularly update software and apply security patches
Conduct security assessments and penetration testing
Educate users on safe SSH server practices

Patching and Updates

Stay informed about security advisories and updates
Follow vendor recommendations for securing SSH servers