CVE-2021-38598

CRITICALNVD 9.19.1—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.1 under NVD CVSS v3. EPSS exploit probability: 1.2%, top 35% 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
9.1
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 1%CVSS: 9.1Exploit: NoneExposed: 0

A fix is available — apply it.

OpenStack Neutron before 16.4.1, 17.x before 17.1.3, and 18.0.0 allows hardware address impersonation when the linuxbridge driver with ebtables-nft is used on a Netfilter-based platform. By sending carefully crafted packets, anyone in control of a server instance connected to the virtual switch can impersonate the hardware addresses of other systems on the network, resulting in denial of service or in some cases possibly interception of traffic intended for other destinations.

CVSS v3
9.1
EG Score
9.1(medium)
EPSS
65.2%
KEV
Not listed

Published

August 23, 2021

Last Modified

November 21, 2024

Advisory Details (1)

Auto-updated Jul 19, 2026
No patch confirmed yet.
generic

Bug #1938670 “[OSSA-2021-004] Linuxbridge ARP filter bypass on N...” : Bugs : neutron

https://launchpad.net/bugs/1938670

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntuneutron-macvtap-agent (2:20.3.0-0ubuntu1.1) @ jammy2026-05-26ubuntu

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 ... 18.0.0 (79 versions)18.1.0—

Weakness Classification(1)

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

All Vendor Advisories

(1)

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 14× in last 7d / 46× 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 101 total refreshes for this CVE.

  1. 2026-07-22 22:50 UTCEG score recompute
  2. 2026-07-22 14:06 UTCEPSS rescore
  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
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  9. 2026-07-19 02:27 UTCEPSS rescore
  10. 2026-07-18 13:59 UTCOSV refresh
  11. 2026-07-18 10:02 UTCEPSS rescore
  12. 2026-07-18 10:02 UTCEPSS rescore
  13. 2026-07-16 17:00 UTCEPSS rescore
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  15. 2026-07-15 16:55 UTCEPSS rescore
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  21. 2026-07-11 08:25 UTCEPSS rescore
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  24. 2026-07-08 15:12 UTCEPSS rescore
  25. 2026-07-07 13:43 UTCEPSS rescore
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  1. 2026-07-06 16:25 UTCEPSS rescore
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  5. 2026-07-04 06:29 UTCEPSS rescore
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  7. 2026-07-01 15:04 UTCEPSS rescore
  8. 2026-06-30 23:20 UTCEPSS rescore
  9. 2026-06-30 23:20 UTCEPSS rescore
  10. 2026-06-30 18:00 UTCOSV refresh
  11. 2026-06-29 14:04 UTCEPSS rescore
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  20. 2026-06-23 21:31 UTCEPSS rescore
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  22. 2026-06-22 14:24 UTCEPSS rescore
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  24. 2026-06-21 14:55 UTCEPSS rescore
  25. 2026-06-21 01:58 UTCEPSS rescore
  26. 2026-06-21 01:58 UTCEPSS rescore
  27. 2026-06-19 19:24 UTCEPSS rescore
  28. 2026-06-19 19:24 UTCEPSS rescore
  29. 2026-06-18 17:51 UTCEPSS rescore
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  31. 2026-06-17 17:51 UTCEPSS rescore
  32. 2026-06-16 17:51 UTCEPSS rescore
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  34. 2026-06-15 17:46 UTCEPSS rescore
  35. 2026-06-14 23:15 UTCEPSS rescore
  36. 2026-06-13 22:58 UTCEPSS rescore
  37. 2026-06-13 22:58 UTCEPSS rescore
  38. 2026-06-13 00:07 UTCOSV refresh
  39. 2026-06-12 23:10 UTCEPSS rescore
  40. 2026-06-12 23:10 UTCEPSS rescore
  41. 2026-06-11 13:58 UTCEPSS rescore
  42. 2026-06-10 22:16 UTCEPSS rescore
  43. 2026-06-10 13:20 UTCEPSS rescore
  44. 2026-06-08 14:15 UTCEPSS rescore
  45. 2026-06-08 14:15 UTCEPSS rescore
  46. 2026-06-07 15:23 UTCEPSS rescore
  47. 2026-06-07 15:23 UTCEPSS rescore
  48. 2026-06-06 13:46 UTCEPSS rescore
  49. 2026-06-06 13:46 UTCEPSS rescore
  50. 2026-06-06 13:46 UTCEPSS rescore
  51. 2026-06-05 22:45 UTCEPSS rescore
  52. 2026-06-05 06:09 UTCEPSS rescore
  53. 2026-06-05 06:09 UTCEPSS rescore
  54. 2026-06-04 13:10 UTCEPSS rescore
  55. 2026-06-04 13:10 UTCEPSS rescore
  56. 2026-06-02 20:11 UTCEPSS rescore
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  58. 2026-06-01 13:50 UTCEPSS rescore
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  60. 2026-05-31 22:29 UTCEPSS rescore
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  62. 2026-05-31 00:15 UTCEPSS rescore
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  64. 2026-05-29 13:42 UTCEPSS rescore
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  71. 2026-05-26 13:42 UTCEPSS rescore
  72. 2026-05-26 11:43 UTCEG score recompute
  73. 2026-05-26 11:43 UTCVendor advisory
  74. 2026-05-26 07:17 UTCEPSS rescore
  75. 2026-05-26 07:17 UTCEPSS rescore

Frequently asked(5)

What is CVE-2021-38598?
CVE-2021-38598 is a critical vulnerability published on August 23, 2021. OpenStack Neutron before 16.4.1, 17.x before 17.1.3, and 18.0.0 allows hardware address impersonation when the linuxbridge driver with ebtables-nft is used on a Netfilter-based platform. By sending carefully crafted packets, anyone in control of a server instance connected to the virtual switch can…
When was CVE-2021-38598 disclosed?
CVE-2021-38598 was first published in the National Vulnerability Database on August 23, 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-2021-38598 actively exploited?
CVE-2021-38598 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 65.2% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-38598?
CVE-2021-38598 has a CVSS v3 base score of 9.1 (NVD).
How do I remediate CVE-2021-38598?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-38598, 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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