CVE-2021-0203
mediumpriority · track · 17EPSS 0.010 · 63 %ileEURUUSEPSS · scored 2026-10-27
On Juniper Networks EX and QFX5K Series platforms configured with Redundant Trunk Group (RTG), Storm Control profile applied on the RTG interface might not take affect when it reaches the threshold condition. Storm Control enables the device to monitor traffic levels and to drop broadcast, multicast, and unknown unicast packets when a specified traffic level is exceeded, thus preventing packets from proliferating and degrading the LAN. Note: this issue does not affect EX2200, EX3300, EX4200, and EX9200 Series. This issue affects Juniper Networks Junos OS on EX Series and QFX5K Series: 15.1 versions prior to 15.1R7-S7; 16.1 versions prior to 16.1R7-S8; 17.2 versions prior to 17.2R3-S4; 17.3 versions prior to 17.3R3-S8; 17.4 versions prior to 17.4R2-S11, 17.4R3-S2; 18.1 versions prior to 18.1R3-S10; 18.2 versions prior to 18.2R3-S5; 18.3 versions prior to 18.3R2-S4, 18.3R3-S2; 18.4 versions prior to 18.4R2-S5, 18.4R3-S3; 19.1 versions prior to 19.1R2-S2, 19.1R3-S2; 19.2 versions prior to 19.2R1-S5, 19.2R2-S1, 19.2R3; 19.3 versions prior to 19.3R2-S4, 19.3R3; 19.4 versions prior to 19.4R1-S3, 19.4R2-S1, 19.4R3; 20.1 versions prior to 20.1R1-S2, 20.1R2.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 4.3–8.6
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (51)
Products and version ranges known to be affected.
also known as (4)
Other names and identifiers for this entity.
sources
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references (7)
External citations — patches, advisories, analysis.
- https://kb.juniper.net/InfoCenter/index?page=content&id=JSA11093&cat=SIRT_ADVISORY&actp=LISTPatchcnnvd
- https://kb.juniper.net/JSA11093cnnvd
- https://nvd.nist.gov/vuln/detail/CVE-2021-0203cnnvd
- https://vigilance.fr/vulnerability/Junos-OS-EX-QFX5K-denial-of-service-via-Storm-Control-Bypass-34323cnnvd
- https://www.auscert.org.au/bulletins/ESB-2021.0178/cnnvd
- https://kb.juniper.net/JSA11093enisa_euvd
- https://kb.juniper.net/JSA11093Vendor Advisorynvd
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