CVE intelligence and bounded remediation

CVE-2021-0202 — Juniper Junos security vulnerability

High CVSS 7.5

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…

Severity
High
CVSS
7.5 (3.1)
Published
2021-01-15
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-400, CWE-401

Affected products

  • juniper / junos / 17.3
  • juniper / junos / 17.4
  • juniper / junos / 18.2
  • juniper / junos / 18.3
  • juniper / junos / 18.4
  • juniper / junos / 19.2

Showing 6 representative product identities from 19 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Resource exhaustion and denial of service

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Identify attacker-influenced work factors including input size, nesting, compression, fan-out, regex cost, allocation, recursion, retries, and connection lifetime.
  • Map per-request and shared CPU, memory, disk, descriptor, thread, queue, and downstream-service limits.
  • Determine whether authentication, tenancy, quotas, and rate controls apply before expensive processing begins.

Remediate safely

  • Bound input size, nesting, expansion, work, concurrency, queue depth, retries, and execution time before resource-intensive processing.
  • Release resources on every success, error, cancellation, and timeout path and use backpressure instead of unbounded buffering.
  • Update affected components and add small deterministic tests that assert resource ceilings rather than exhausting a host.

Authoritative sources

Complete CVE record and remediation plan

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