CVE-2021-31371

MEDIUMNVD 5.35.3—
EchelonGraph scoreMEDIUM confidence

Score 5.3 from GitHub Security Advisory published 2022-05-24. NVD baseline CVSS 5.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
5.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 5.3Exploit: None knownExposed: 0

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

Juniper Networks Junos OS uses the 128.0.0.0/2 subnet for internal communications between the RE and PFEs. It was discovered that packets utilizing these IP addresses may egress an QFX5000 Series switch, leaking configuration information such as heartbeats, kernel versions, etc. out to the Internet, leading to an information exposure vulnerability. This issue affects Juniper Networks Junos OS on QFX5110, QFX5120, QFX5200, QFX5210 Series, and QFX5100 with QFX 5e Series image installed: All versions prior to 17.3R3-S12; 18.1 versions prior to 18.1R3-S13; 18.3 versions prior to 18.3R3-S5; 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-S5; 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-S1; 20.4 versions prior to 20.4R2-S1, 20.4R3; 21.1 versions prior to 21.1R1-S1, 21.1R2;

CVSS v3
5.3
EG Score
5.3(medium)
EG Risk
29(Track)
EG Risk 29/100SSVC: Track

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
Severity53% × 45%
Exploitation1% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
56%
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 8× in last 7d / 30× 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.

Showing the most recent 100 of 148 total refreshes for this CVE.

  1. 2026-09-07 15:58 UTCEPSS rescore
  2. 2026-09-06 13:44 UTCEPSS rescore
  3. 2026-09-05 15:25 UTCEPSS rescore
  4. 2026-09-04 13:57 UTCEPSS rescore
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  24. 2026-08-16 02:11 UTCEPSS rescore
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  1. 2026-08-15 01:27 UTCEPSS rescore
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  3. 2026-08-12 13:47 UTCEPSS rescore
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  5. 2026-08-09 13:43 UTCEPSS rescore
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  8. 2026-08-06 13:43 UTCEPSS rescore
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  20. 2026-07-26 14:52 UTCEPSS rescore
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  22. 2026-07-25 14:15 UTCEPSS rescore
  23. 2026-07-24 14:15 UTCEPSS rescore
  24. 2026-07-23 14:16 UTCEPSS rescore
  25. 2026-07-23 02:00 UTCEG score recompute
  26. 2026-07-22 22:47 UTCEG score recompute
  27. 2026-07-22 14:06 UTCEPSS rescore
  28. 2026-07-22 14:06 UTCEPSS rescore
  29. 2026-07-21 15:22 UTCEPSS rescore
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  31. 2026-07-20 17:05 UTCEPSS rescore
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  40. 2026-07-15 01:58 UTCEPSS rescore
  41. 2026-07-13 22:27 UTCEPSS rescore
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  43. 2026-07-13 06:10 UTCEPSS rescore
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  46. 2026-07-11 08:25 UTCEPSS rescore
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  48. 2026-07-09 19:07 UTCEPSS rescore
  49. 2026-07-08 15:12 UTCEPSS rescore
  50. 2026-07-07 13:43 UTCEPSS rescore
  51. 2026-07-06 16:25 UTCEPSS rescore
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  53. 2026-07-06 02:21 UTCEPSS rescore
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  58. 2026-07-02 16:57 UTCEPSS rescore
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  60. 2026-06-30 23:20 UTCEPSS rescore
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  72. 2026-06-23 21:31 UTCEPSS rescore
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  74. 2026-06-22 14:24 UTCEPSS rescore
  75. 2026-06-22 14:24 UTCEPSS rescore

Frequently asked(5)

What is CVE-2021-31371?
CVE-2021-31371 is a medium vulnerability published on October 19, 2021. Juniper Networks Junos OS uses the 128.0.0.0/2 subnet for internal communications between the RE and PFEs. It was discovered that packets utilizing these IP addresses may egress an QFX5000 Series switch, leaking configuration information such as heartbeats, kernel versions, etc. out to the…
When was CVE-2021-31371 disclosed?
CVE-2021-31371 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-2021-31371 actively exploited?
CVE-2021-31371 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 44.5% of all scored CVEs.
What is the CVSS score of CVE-2021-31371?
CVE-2021-31371 has a CVSS v3 base score of 5.3 (NVD).
How do I remediate CVE-2021-31371?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-31371, 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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