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AUSCERT External Security Bulletin Redistribution
JSA11148 - 2021-04 Security Bulletin: Junos OS: MX Series, EX9200 Series:
Trio-based MPCs memory leak in VPLS with integrated routing
and bridging (IRB) interface
15 April 2021
AusCERT Security Bulletin Summary
Product: Junos OS: MX Series
Junos OS: EX9200 Series
Publisher: Juniper Networks
Operating System: Juniper
Impact/Access: Denial of Service -- Remote/Unauthenticated
CVE Names: CVE-2021-0257
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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)
Article ID : JSA11148
Last Updated: 14 Apr 2021
Version : 2.0
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.
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
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
o 17.3 versions prior to 17.3R3-S10;
o 17.4 versions prior to 17.4R3-S3;
o 18.2 versions prior to 18.2R3-S7;
o 18.3 versions prior to 18.3R3-S4;
o 18.4 versions prior to 18.4R3-S6;
o 19.2 versions prior to 19.2R3-S2;
o 19.3 versions prior to 19.3R3-S1;
o 19.4 versions prior to 19.4R2-S2, 19.4R3;
o 20.2 versions prior to 20.2R1-S3, 20.2R2;
o 20.3 versions prior to 20.3R1-S1,, 20.3R2.
This issue does not affect Juniper Networks Junos OS:
o 17.3 versions prior to 17.3R3-S8;
o 17.4 versions prior to 17.4R3-S2;
o any version of 18.1;
o 18.2 versions prior to 18.2R3-S4;
o 18.3 versions prior to 18.3R3-S2;
o 18.4 versions prior to 18.4R3-S1;
o any version of 19.1;
o 19.2 versions prior to 19.2R2;
o 19.3 versions prior to 19.3R3;
o 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 .
There are no viable workarounds for this issue.
Software releases or updates are available for download at https://
2021-04-14: Initial Publication.
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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