On Juniper Networks MX Series and EX9200 Series platforms with Trio-based MPCs (Modular Port Concentrators) where Integrated Routing and Bridging (IRB) interfaces are configured and mapped to a VPLS instance or a Bridge-Domain, certain Layer 2 network events at Customer Edge (CE) devices may cause memory leaks in the MPC of Provider Edge (PE) devices which can cause an out of memory condition and MPC restart.

When this issue occurs, there will be temporary traffic interruption until the MPC is restored.

An administrator can use the following CLI command to monitor the status of memory usage level of the MPC:

When the issue is occurring, the value of “ % NH mem Free ” will go down until the MPC restarts.

This issue affects MX Series and EX9200 Series with Trio-based PFEs (Packet Forwarding Engines), including MX-MPC1-3D, MX-MPC1E-3D, MX-MPC2-3D, MX-MPC2E-3D, MPC-3D-16XGE, and CHAS-MXxx Series MPCs. No other products or platforms are affected by this issue.

This issue affects:

Juniper Networks Junos OS on MX Series, EX9200 Series

• 17.3 versions prior to 17.3R3-S10;
• 17.4 versions prior to 17.4R3-S3;
• 18.2 versions prior to 18.2R3-S7;
• 18.3 versions prior to 18.3R3-S4;
• 18.4 versions prior to 18.4R3-S6;
• 19.2 versions prior to 19.2R3-S2;
• 19.3 versions prior to 19.3R3-S1;
• 19.4 versions prior to 19.4R2-S2, 19.4R3;
• 20.2 versions prior to 20.2R1-S3, 20.2R2;
• 20.3 versions prior to 20.3R1-S1,, 20.3R2.

This issue does not affect Juniper Networks Junos OS:

• 17.3 versions prior to 17.3R3-S8;
• 17.4 versions prior to 17.4R3-S2;
• any version of 18.1;
• 18.2 versions prior to 18.2R3-S4;
• 18.3 versions prior to 18.3R3-S2;
• 18.4 versions prior to 18.4R3-S1;
• any version of 19.1;
• 19.2 versions prior to 19.2R2;
• 19.3 versions prior to 19.3R3;
• 19.4 versions prior to 19.4R2.

A sample configuration of an IRB interface configured for VPLS is shown below:

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-2021-0257 .
 

The following software releases have been updated to resolve this specific issue: Junos OS 17.3R3-S10, 17.4R3-S3, 18.2R3-S7, 18.3R3-S4, 18.4R3-S6, 19.2R3-S2, 19.3R3-S1, 19.4R2-S2, 19.4R3, 20.1R2, 20.2R1-S3, 20.2R2, 20.2R3, 20.3R1-S1, 20.3R2, 20.4R1, and all subsequent releases.

This issue is being tracked as  1528641 .
 

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-2021-0257 at cve.mitre.org