CVE-2021-28902 : Vulnerability Insights and Analysis

A vulnerability in libyang <= v1.0.225 can lead to a crash due to improper NULL value validation. This article provides insights into CVE-2021-28902 and essential mitigation steps.

Understanding CVE-2021-28902

CVE-2021-28902 is a security flaw in the libyang library that can trigger a crash by not verifying NULL values properly.

What is CVE-2021-28902?

The vulnerability lies in the read_yin_container() function of libyang <= v1.0.225. When the value of retval->ext[r] is NULL, accessing retval->ext[r]->flags can cause a crash.

The Impact of CVE-2021-28902

Exploitation of this vulnerability can lead to a denial of service (DoS) condition, potentially affecting the stability and availability of systems running the vulnerable versions of libyang.

Technical Details of CVE-2021-28902

The technical details of CVE-2021-28902 include the vulnerability description, affected systems and versions, and the exploitation mechanism.

Vulnerability Description

In the function read_yin_container() in libyang <= v1.0.225, the absence of proper NULL value validation for retval->ext[r] can result in a crash when accessing retval->ext[r]->flags under certain conditions.

Affected Systems and Versions

All versions of libyang up to v1.0.225 are impacted by CVE-2021-28902. Users are advised to check and update to the latest version for a patch.

Exploitation Mechanism

By manipulating specific conditions to trigger the NULL value scenario, threat actors can exploit this vulnerability to disrupt services and cause system instability.

Mitigation and Prevention

Understanding the necessary steps to mitigate the CVE-2021-28902 vulnerability is crucial for enhancing system security.

Immediate Steps to Take

Ensure that the libyang library is updated to a version that includes a patch for CVE-2021-28902. Additionally, monitor system logs for any unusual activities that could indicate exploitation.

Long-Term Security Practices

Implement a robust security posture by keeping all software components up to date, conducting regular security assessments, and employing intrusion detection systems to detect and prevent potential attacks.

Patching and Updates

Regularly check for updates and security advisories from the libyang official sources and apply patches promptly to address any newly discovered vulnerabilities and enhance overall system security.