CVE-2021-0221

MEDIUMNVD 6.56.5—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.5 under NVD CVSS v3. EPSS exploit probability: 0.5% (41st percentile of EPSS-scored CVEs). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: Headline CVSS from NVD CVSS v3
Sources: EPSS, NVD CVSS v3
6.5EG
EchelonGraph verdictMonitorRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 6.5Exploit: None knownExposed services: Not assessed

The following software releases have been updated to resolve this specific issue: Junos OS 17.3R3-S10, 17.4R2-S12, 17.4R3-S3, 18.1R3-S11, 18.2R3-S6, 18.3R3-S4, 18.4R2-S5, 18.4R3-S5, 19.1R1-S6, 19.1R2-S2, 19.1R3-S3, 19.2… (from the CVE record's solution, Juniper Networks, Inc.) — apply it.

In an EVPN/VXLAN scenario, if an IRB interface with a virtual gateway address (VGA) is configured on a PE, a traffic loop may occur upon receipt of specific IP multicast traffic. The traffic loop will cause interface traffic to increase abnormally, ultimately leading to a Denial of Service (DoS) in packet processing. The following command could be used to monitor the interface traffic: user@junos> monitor interface traffic Interface Link Input packets (pps) Output packets (pps) et-0/0/1 Up 6492089274364 (70994959) 6492089235319 (70994956) et-0/0/25 Up 343458103 (1) 156844 (0) ae0 Up 9132519197257 (70994959) 9132519139454 (70994956) This issue affects Juniper Networks Junos OS on QFX Series: all versions prior to 17.3R3-S10; 17.4 versions prior to 17.4R2-S12, 17.4R3-S3; 18.1 versions prior to 18.1R3-S11; 18.2 versions prior to 18.2R3-S6; 18.3 versions prior to 18.3R3-S4; 18.4 versions prior to 18.4R2-S5, 18.4R3-S5; 19.1 versions prior to 19.1R1-S6, 19.1R2-S2, 19.1R3-S3; 19.2 versions prior to 19.2R1-S5, 19.2R3-S1; 19.3 versions prior to 19.3R2-S5, 19.3R3; 19.4 versions prior to 19.4R2-S2, 19.4R3; 20.1 versions prior to 20.1R2; 20.2 versions prior to 20.2R1-S2, 20.2R2.

CVSS v3
6.5
EG Score
6.5MEDIUMmedium confidence
EG Risk
34
EG Risk 34/100

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed (value × EchelonGraph’s weight)
Severity65% × 45%
The EG Score, 6.5 of 10.
Exploitation0.5% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability30% × 15%
EchelonGraph's default before algorithm v3.4: CISA had not published Automatable for this CVE.
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track or Attend at high (mission-essential systems).
Exploitation none (no KEV listing, exploit record or EPSS ≥ 50%) · Automatable unknown (not published for this CVE) · Technical impact partial (CVSS below 9.0). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: The following software releases have been updated to resolve this specific issue: Junos OS 17.3R3-S10, 17.4R2-S12, 17.4R3-S3, 18.1R3-S11, 18.2R3-S6, 18.3R3-S4, 18.4R2-S5, 18.4R3-S5, 19.1R1-S6, 19.1R2-S2, 19.1R3-S3, 19.2… (from the CVE record's solution, Juniper Networks, Inc.). Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.5%
EPSS %ILE
42nd
KEV
Not listed

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track or Attend at high (mission-essential systems).

The following software releases have been updated to resolve this specific issue: Junos OS 17.3R3-S10, 17.4R2-S12, 17.4R3-S3, 18.1R3-S11, 18.2R3-S6, 18.3R3-S4, 18.4R2-S5, 18.4R3-S5, 19.1R1-S6, 19.1R2-S2, 19.1R3-S3, 19.2… (from the CVE record's solution, Juniper Networks, Inc.). Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (no KEV listing, exploit record or EPSS ≥ 50%) · Automatable unknown (not published for this CVE) · Technical impact partial (CVSS below 9.0). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

Published

January 15, 2021

Last Modified

November 21, 2024

References (1)

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 8× in last 7d / 26× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 85 of 152 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 15 repeat rows among the latest 100 are merged into the row they repeat. The 67 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

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Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2021-0221?
CVE-2021-0221 is a medium-severity vulnerability; its CVE record was published on January 15, 2021. In an EVPN/VXLAN scenario, if an IRB interface with a virtual gateway address (VGA) is configured on a PE, a traffic loop may occur upon receipt of specific IP multicast traffic. The traffic loop will cause interface traffic to increase abnormally, ultimately leading to a Denial of Service (DoS) in…
When was CVE-2021-0221 made public?
CVE-2021-0221 was made public on January 13, 2021: that is the date its CVE record's CNA, Juniper Networks, Inc., gives for when the vulnerability was made public. The CVE record itself was published on January 15, 2021. EchelonGraph's copy of the record carries a last-modified date of November 21, 2024; the record at its source may have been updated since.
Is CVE-2021-0221 actively exploited?
CVE-2021-0221 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (42nd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2021-0221?
CVE-2021-0221 has a CVSS v3 base score of 6.5 (NVD).
How do I remediate CVE-2021-0221?
The CVE record's solution for CVE-2021-0221, written by its CNA Juniper Networks, Inc., names the fix: "The following software releases have been updated to resolve this specific issue: Junos OS 17.3R3-S10, 17.4R2-S12, 17.4R3-S3, 18.1R3-S11, 18.2R3-S6, 18.3R3-S4, 18.4R2-S5, 18.4R3-S5, 19.1R1-S6, 19.1R2-S2, 19.1R3-S3, 19.2…"

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