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 thereby causing a Denial of Service (DoS), crashing the Multiservices PIC Management Daemon (mspmand) process thereby denying users the ability to login, while concurrently impacting other mspmand services and traffic through the device.

Continued receipt and processing of these malformed packets will create a sustained Denial of Service (DoS) condition.

While the Services PIC is restarting, all PIC services will be bypassed until the Services PIC completes its boot process.

An attacker sending these malformed HTTP packets to the device who is not part of the Captive Portal experience is not able to exploit this issue.

This issue is not applicable to MX RE-based CPCD platforms.

This issue affects:

Juniper Networks Junos OS on MX Series:

• 17.3 version 17.3R1 and later versions prior to 17.4 versions 17.4R2-S9, 17.4R3-S2;
• 18.1 versions prior to 18.1R3-S9;
• 18.2 versions prior to 18.2R3-S3;
• 18.3 versions prior to 18.3R3-S1;
• 18.4 versions prior to 18.4R3;
• 19.1 versions prior to 19.1R2-S2, 19.1R3;
• 19.2 versions prior to 19.2R2;
• 19.3 versions prior to 19.3R3.

• This issue does not affect Juniper Networks Junos OS versions prior to 17.3R1.

The subscriber management services with the captive portal must be enabled to be vulnerable to this issue.

Example locations:

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

This issue was seen during production usage.

This issue has been assigned  CVE-2021-0251 .

The following software releases have been updated to resolve this specific issue: 17.4R2-S9, 17.4R3-S2, 18.1R3-S9, 18.2R3-S3, 18.3R3-S1, 18.4R3, 19.1R2-S2, 19.1R3, 19.2R2, 19.3R3, 19.4R1, and all subsequent releases.

This issue is being tracked as  1445812 .

Software releases or updates are available for download at https://support.juniper.net/support/downloads/

2021-04-14: Initial Publication.

• KB16613: Overview of the Juniper Networks SIRT Quarterly Security Bulletin Publication Process [juniper.net]
• KB16765: In which releases are vulnerabilities fixed? [juniper.net]
• KB16446: Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories [juniper.net]
• Report a Security Vulnerability - How to Contact the Juniper Networks Security Incident Response Team
• CVE-2021-0251 at cve.mitre.org