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2021-04 Security Bulletin: Junos OS: MX Series, EX9200 Series: Trio-based MPCs memory leak in VPLS with integrated routing and bridging (IRB) interface (CVE-2021-0257)

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Article ID: JSA11148 SECURITY_ADVISORIES Last Updated: 14 Apr 2021Version: 2.0
Product Affected:
This issue affects Junos OS 17.3, 17.4, 18.2, 18.3, 18.4, 19.2, 19.3, 19.4, 20.1, 20.2, 20.3. Affected platforms: EX9200 Series, MX Series.
Problem:

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:


user@device> show system resource-monitor fpc
FPC Resource Usage Summary
Free Heap Mem Watermark : 20 %
Free NH Mem Watermark : 20 %
Free Filter Mem Watermark : 20 %
* - Watermark reached

Slot # % Heap Free RTT Average RTT
1 87

 

PFE # % ENCAP mem Free % NH mem Free % FW mem Free
0 NA 88 99
1 NA 89 99

 

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:

routing-instances {
  instance1 {
    instance-type vpls;
    routing-interface irb.1234;
  }
}


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.
 

Solution:

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.
 

Workaround:
There are no viable workarounds for this issue.
 
Implementation:
Software releases or updates are available for download at https://support.juniper.net/support/downloads/
 
Modification History:
2021-04-14: Initial Publication.

CVSS Score:
6.5 (CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
Severity Level:
Medium
Severity Assessment:
Information for how Juniper Networks uses CVSS can be found at KB 16446 "Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories."

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