CVE-2021-40085

MEDIUMNVD 6.56.5—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.5 under NVD CVSS v3. EPSS exploit probability: 1.8%, top 24% 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
Trending — 3 sources updated this week
6.5
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 2%CVSS: 6.5Exploit: NoneExposed: 0

A fix is available — apply it.

An issue was discovered in OpenStack Neutron before 16.4.1, 17.x before 17.2.1, and 18.x before 18.1.1. Authenticated attackers can reconfigure dnsmasq via a crafted extra_dhcp_opts value.

CVSS v3
6.5
EG Score
6.5(medium)
EG Risk
34(Track)
EG Risk 34/100SSVC: 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
Severity65% × 45%
Exploitation2% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
76.4%
KEV
Not listed

Published

August 31, 2021

Last Modified

November 21, 2024

References (12)

Patch Availability(5)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntuneutron-macvtap-agent (2:20.3.0-0ubuntu1.1) @ jammy2026-05-26ubuntu
redhatopenstack-neutron-1:15.3.5-2.20210608154813.el8ost.32021-09-15redhat
redhatopenstack-neutron-1:12.1.1-42.1.el7ost2021-09-13redhat
redhatopenstack-neutron-1:9.4.1-56.el7ost2021-09-13redhat
redhatopenstack-neutron-1:15.2.1-1.20210409073447.el8ost2021-09-09redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(1 across 1 ecosystem)
PyPI(1)
PackageVulnerable rangeFixed inDependents
neutron0.0 ... 18.1.0 (81 versions)18.1.1—

All Vendor Advisories

(5)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 13× in last 7d / 51× 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 107 total refreshes for this CVE.

  1. 2026-07-23 02:04 UTCEG score recompute
  2. 2026-07-22 22:50 UTCEG score recompute
  3. 2026-07-22 14:06 UTCEPSS rescore
  4. 2026-07-21 15:22 UTCEPSS rescore
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  6. 2026-07-20 17:05 UTCEPSS rescore
  7. 2026-07-19 14:29 UTCEPSS rescore
  8. 2026-07-19 02:27 UTCEPSS rescore
  9. 2026-07-18 13:29 UTCOSV refresh
  10. 2026-07-18 10:02 UTCEPSS rescore
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  12. 2026-07-16 17:00 UTCEPSS rescore
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  24. 2026-07-09 19:07 UTCEPSS rescore
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  1. 2026-07-07 13:43 UTCEPSS rescore
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  12. 2026-06-30 23:20 UTCEPSS rescore
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  14. 2026-06-30 17:00 UTCOSV refresh
  15. 2026-06-29 14:04 UTCEPSS rescore
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  19. 2026-06-27 03:06 UTCEPSS rescore
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  21. 2026-06-25 13:48 UTCEPSS rescore
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  27. 2026-06-22 14:24 UTCEPSS rescore
  28. 2026-06-21 14:55 UTCEPSS rescore
  29. 2026-06-21 01:58 UTCEPSS rescore
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  31. 2026-06-19 19:24 UTCEPSS rescore
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  40. 2026-06-15 17:46 UTCEPSS rescore
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  43. 2026-06-13 22:58 UTCEPSS rescore
  44. 2026-06-13 22:58 UTCEPSS rescore
  45. 2026-06-12 23:10 UTCEPSS rescore
  46. 2026-06-12 23:07 UTCOSV refresh
  47. 2026-06-11 13:58 UTCEPSS rescore
  48. 2026-06-11 13:58 UTCEPSS rescore
  49. 2026-06-10 22:16 UTCEPSS rescore
  50. 2026-06-10 22:16 UTCEPSS rescore
  51. 2026-06-10 13:20 UTCEPSS rescore
  52. 2026-06-08 14:15 UTCEPSS rescore
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  54. 2026-06-07 15:23 UTCEPSS rescore
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  56. 2026-06-06 13:46 UTCEPSS rescore
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  58. 2026-06-05 22:45 UTCEPSS rescore
  59. 2026-06-05 06:09 UTCEPSS rescore
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  61. 2026-06-04 13:10 UTCEPSS rescore
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  63. 2026-06-02 20:11 UTCEPSS rescore
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  65. 2026-06-01 13:50 UTCEPSS rescore
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  67. 2026-05-31 22:29 UTCEPSS rescore
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  71. 2026-05-29 13:42 UTCEPSS rescore
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  73. 2026-05-28 13:43 UTCEPSS rescore
  74. 2026-05-27 13:39 UTCEPSS rescore
  75. 2026-05-27 13:39 UTCEPSS rescore

Related CVEs(same vendor)

Frequently asked(5)

What is CVE-2021-40085?
CVE-2021-40085 is a medium vulnerability published on August 31, 2021. An issue was discovered in OpenStack Neutron before 16.4.1, 17.x before 17.2.1, and 18.x before 18.1.1. Authenticated attackers can reconfigure dnsmasq via a crafted extradhcpopts value.
When was CVE-2021-40085 disclosed?
CVE-2021-40085 was first published in the National Vulnerability Database on August 31, 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-2021-40085 actively exploited?
CVE-2021-40085 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 76.4% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-40085?
CVE-2021-40085 has a CVSS v3 base score of 6.5 (NVD).
How do I remediate CVE-2021-40085?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-40085, 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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