CVE-2021-31370

MEDIUMNVD 6.56.5—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.5 under NVD CVSS v3. EPSS exploit probability: 0.1%, top 76% of all CVEs by exploit prediction. 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: NVD CVSS baseline
Sources: epss, nvd
6.5
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 6.5Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

An Incomplete List of Disallowed Inputs vulnerability in Packet Forwarding Engine (PFE) of Juniper Networks Junos OS on QFX5000 Series and EX4600 Series allows an adjacent unauthenticated attacker which sends a high rate of specific multicast traffic to cause control traffic received from the network to be dropped. This will impact control protocols (including but not limited to routing-protocols) and lead to a Denial of Service (DoS). Continued receipt of this specific multicast traffic will create a sustained Denial of Service (DoS) condition. This issue affects Juniper Networks Junos OS on QFX5000 and EX4600 Series: All versions prior to 17.3R3-S12; 17.4 versions prior to 17.4R3-S5; 18.3 versions prior to 18.3R3-S5; 18.4 versions prior to 18.4R3-S9; 19.1 versions prior to 19.1R3-S6; 19.2 versions prior to 19.2R1-S7, 19.2R3-S3; 19.3 versions prior to 19.3R2-S6, 19.3R3-S3; 19.4 versions prior to 19.4R1-S4, 19.4R3-S3; 20.1 versions prior to 20.1R2-S2, 20.1R3-S1; 20.2 versions prior to 20.2R3-S2; 20.3 versions prior to 20.3R3; 20.4 versions prior to 20.4R2-S2, 20.4R3; 21.1 versions prior to 21.1R1-S1, 21.1R2.

CVSS v3
6.5
EG Score
6.5(medium)
EPSS
32.9%
KEV
Not listed

Published

October 19, 2021

Last Modified

November 21, 2024

References (2)

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 10× in last 7d / 45× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

  1. 2026-07-11 08:25 UTCEPSS rescore
  2. 2026-07-11 08:25 UTCEPSS rescore
  3. 2026-07-09 19:07 UTCEPSS rescore
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  1. 2026-06-24 14:03 UTCEPSS rescore
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  4. 2026-06-22 14:24 UTCEPSS rescore
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  6. 2026-06-21 14:55 UTCEPSS rescore
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  10. 2026-06-19 19:24 UTCEPSS rescore
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  21. 2026-06-11 13:58 UTCEPSS rescore
  22. 2026-06-10 22:16 UTCEPSS rescore
  23. 2026-06-10 13:20 UTCEPSS rescore
  24. 2026-06-08 14:15 UTCEPSS rescore
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  27. 2026-06-06 13:46 UTCEPSS rescore
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  41. 2026-05-31 00:15 UTCEPSS rescore
  42. 2026-05-29 13:42 UTCEPSS rescore
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  45. 2026-05-27 13:39 UTCEPSS rescore
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  47. 2026-05-26 13:42 UTCEPSS rescore
  48. 2026-05-26 08:51 UTCEG score recompute
  49. 2026-05-26 08:51 UTCGHSA enrichment
  50. 2026-05-26 07:17 UTCEPSS rescore
  51. 2026-05-26 07:17 UTCEPSS rescore

Frequently asked(5)

What is CVE-2021-31370?
CVE-2021-31370 is a medium vulnerability published on October 19, 2021. An Incomplete List of Disallowed Inputs vulnerability in Packet Forwarding Engine (PFE) of Juniper Networks Junos OS on QFX5000 Series and EX4600 Series allows an adjacent unauthenticated attacker which sends a high rate of specific multicast traffic to cause control traffic received from the…
When was CVE-2021-31370 disclosed?
CVE-2021-31370 was first published in the National Vulnerability Database on October 19, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-31370 actively exploited?
CVE-2021-31370 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 32.9% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-31370?
CVE-2021-31370 has a CVSS v3 base score of 6.5 (NVD).
How do I remediate CVE-2021-31370?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-31370, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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