CVE-2021-0202
Published: 15 January 2021
Summary
CVE-2021-0202 is a high-severity Uncontrolled Resource Consumption (CWE-400) vulnerability in Juniper Junos. Its CVSS base score is 7.5 (High).
Operationally, ranked in the top 39.6% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2021-2821
Vulnerability details
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…
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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.
- CWE(s)
Related Threats
No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Limiting concurrent sessions directly prevents uncontrolled resource consumption by capping the number of active sessions per user or account.
Analysis identifies uncontrolled resource consumption indicative of denial-of-service or abuse attempts.
Contingency plan testing includes resource exhaustion scenarios to verify recovery, making it harder for attackers to sustain exploits that cause uncontrolled consumption.
Updated contingency plans include current procedures to detect, contain, and recover from resource exhaustion, limiting an attacker's ability to sustain impact from uncontrolled consumption.
Alternate site allows resumption of operations if resource exhaustion at the primary site is exploited to cause unavailability.
Alternate telecommunications services enable resumption of essential functions when primary services become unavailable due to uncontrolled resource consumption.
The team can analyze and respond to resource exhaustion incidents, reducing the impact of attacks that exploit uncontrolled consumption weaknesses.
Timely maintenance support and spare parts enable rapid recovery from failures induced by uncontrolled resource consumption, shortening the impact window of denial-of-service attacks.