CVE-2019-3863 : Security Advisory and Response

An issue was discovered in libssh2 prior to version 1.8.1 where a server transmitting multiple response messages for keyboard interactive authentication could lead to a memory write error due to out-of-bounds memory copying.

Understanding CVE-2019-3863

This CVE involves a vulnerability in libssh2 that could be exploited by a remote attacker to cause a denial of service or potentially execute arbitrary code on the target system.

What is CVE-2019-3863?

CVE-2019-3863 is a flaw in libssh2 versions prior to 1.8.1 that allows a server to trigger a memory write error by sending multiple response messages during keyboard interactive authentication.

The Impact of CVE-2019-3863

The impact of this vulnerability is rated as HIGH with a CVSS base score of 7.5. It can result in confidentiality, integrity, and availability compromises on affected systems.

Technical Details of CVE-2019-3863

This section provides more in-depth technical insights into the CVE-2019-3863 vulnerability.

Vulnerability Description

The flaw in libssh2 before version 1.8.1 allows a server to exceed the maximum allowed characters for an unsigned char during keyboard interactive authentication, leading to a memory write error.

Affected Systems and Versions

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

Exploitation Mechanism

Attack Complexity: HIGH
Attack Vector: NETWORK
Privileges Required: NONE
User Interaction: REQUIRED
Scope: UNCHANGED
Confidentiality Impact: HIGH
Integrity Impact: HIGH
Availability Impact: HIGH

Mitigation and Prevention

To address CVE-2019-3863, follow these mitigation strategies:

Immediate Steps to Take

Update libssh2 to version 1.8.1 or later.
Monitor vendor advisories for patches and updates.

Long-Term Security Practices

Implement network segmentation to limit the impact of potential attacks.
Regularly review and update security configurations.

Patching and Updates

Apply security patches promptly to mitigate known vulnerabilities.