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2021-01 Security Bulletin: Junos OS: MX Series, EX9200 Series: Trio-based MPC memory leak when Integrated Routing and Bridging (IRB) interface is mapped to a VPLS instance or a Bridge-Domain (CVE-2021-0202)

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Article ID: JSA11092 SECURITY_ADVISORIES Last Updated: 13 Jan 2021Version: 1.0
Product Affected:
This issue affects Junos OS 17.3, 17.4, 18.2, 18.3, 18.4, 19.2, 19.4, 20.2. Affected platforms: EX9200 Series, MX Series.
Problem:

On Juniper Networks MX Series and EX9200 Series platforms with Trio-based MPC (Modular Port Concentrator) where Integrated Routing and Bridging (IRB) interface is configured and it is mapped to a VPLS instance or a Bridge-Domain, certain network events at Customer Edge (CE) device may cause memory leak in the MPC which can cause an out of memory and MPC restarts.

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).

Please refer to https://kb.juniper.net/KB25385 for the list of Trio-based PFEs.
 

This issue affects Juniper Networks Junos OS on MX Series, EX9200 Series:

17.3R3-S8;

17.4R3-S2;

18.2R3-S4, 18.2R3-S5;

18.3R3-S2, 18.3R3-S3;

18.4 versions starting from 18.4R3-S1 and later versions prior to 18.4R3-S6;

19.2 versions starting from 19.2R2 and later versions prior to 19.2R3-S1;

19.4 versions starting from 19.4R2 and later versions prior to 19.4R2-S3, 19.4R3;

20.2 versions starting from 20.2R1 and later versions prior to 20.2R1-S3, 20.2R2.

This issue does not affect Juniper Networks Junos OS: 18.1, 19.1, 19.3, 20.1.
 

This issue may occur when the IRB interface is configured and mapped to a VPLS instance or a Bridge-Domain

In the scenario where the IRB interface is mapped to a Bridge-Domain, the minimum configuration stanzas required related to this issue are the following:

[bridge-domains <domain_name> routing-interface irb.<unit_number>]

in combination with:

[bridge-domains <domain_name> domain-type bridge]

In the scenario where the IRB interface is mapped to a VPLS instance, the minimum configuration stanzas required related to this issue are the following:

[routing-instances <instace_name> instance-type vpls]

in combination with:

[routing-instances <instace_name> routing-interface irb.<unit_number>]
 

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-2021-0202.

Solution:

The following software releases have been updated to resolve this specific issue: 17.3R3-S9, 17.4R3-S3, 18.2R3-S6, 18.3R3-S4, 18.4R3-S6, 19.2R3-S1, 19.4R2-S3, 19.4R3, 20.2R1-S3, 20.2R2, 20.3R1, and all subsequent releases.

The fix has been proactively committed to other releases as well.

This issue is being tracked as 1525226.

Workaround:

There are no viable workarounds for this issue.

Implementation:
Software releases or updates are available for download at https://www.juniper.net/support/downloads/.
Modification History:
2021-01-13: Initial Publication.
CVSS Score:
7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
Severity Level:
High
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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