CVE-2021-0251 Explained : Impact and Mitigation

A NULL Pointer Dereference vulnerability in the Captive Portal Content Delivery (CPCD) services daemon (cpcd) of Juniper Networks Junos OS on MX Series with MS-PIC, MS-SPC3, MS-MIC or MS-MPC allows an attacker to send malformed HTTP packets to the device, causing a Denial of Service (DoS) by crashing the Multiservices PIC Management Daemon (mspmand) process. This impacts user login abilities and overall device traffic. Learn more about the impact, affected systems, and mitigation steps.

Understanding CVE-2021-0251

This section provides detailed information about the vulnerability, its impact, affected systems, and practical solutions to prevent exploitation.

What is CVE-2021-0251?

CVE-2021-0251 is a NULL Pointer Dereference vulnerability in the Captive Portal Content Delivery (CPCD) services daemon of Juniper Networks Junos OS on MX Series, allowing attackers to cause a Denial of Service attack by sending malformed HTTP packets to the device.

The Impact of CVE-2021-0251

The vulnerability can result in a Denial of Service (DoS) by crashing the Multiservices PIC Management Daemon process, affecting user login capabilities and device traffic on MX Series platforms.

Technical Details of CVE-2021-0251

In this section, we delve into the vulnerability description, affected systems, and exploitation mechanism involved.

Vulnerability Description

The vulnerability in the Captive Portal Content Delivery (CPCD) services daemon (cpcd) of Juniper Networks Junos OS allows attackers to send malformed HTTP packets, leading to a Denial of Service condition by crashing the Multiservices PIC Management Daemon process.

Affected Systems and Versions

The vulnerability affects Juniper Networks Junos OS on MX Series versions 17.3R1 and later versions prior to 19.3R3.

Exploitation Mechanism

An attacker can exploit this vulnerability by sending malformed HTTP packets to the device hosting this vulnerable software, triggering a Denial of Service (DoS) condition.

Mitigation and Prevention

This section outlines the immediate steps to take, long-term security practices, and the importance of patching and updates to mitigate the risk.

Immediate Steps to Take

To mitigate the risk, it is recommended to update the software to the fixed versions provided by Juniper Networks.

Long-Term Security Practices

Implement a proactive approach to software updates, security monitoring, and network hardening to prevent such vulnerabilities.

Patching and Updates

Install the updated software releases provided by Juniper Networks to address this vulnerability and prevent potential exploitation.