OpenStack Neutron vulnerable to hardware address impersonation

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

8.8 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2021-38598: 1.22% estimated exploitation activity in the next 30 days; percentile 68.72 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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.

Published by the source

24 May 2022, 19:11 UTC

Last modified by the source

3 Oct 2024, 21:33 UTC

Source last checked

26 Oct 2026, 13:21 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-hvm4-mc7m-22w4

2. Revision 2 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-hvm4-mc7m-22w4

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# Patch Next advisory brief: CVE-2021-38598

Advisory: OpenStack Neutron vulnerable to hardware address impersonation
IDs: CVE-2021-38598, GHSA-hvm4-mc7m-22w4
Record: https://patchnext.com/advisories/cve-2021-38598 (revision 3, source checked 26 Oct 2026, 13:21 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Partial vendor fix; fixed versions by package: neutron 17.1.3, 16.4.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI neutron: affected < 16.4.1; >= 17.0.0, < 17.1.3; >= 18.0.0, <= 18.0.0; fixed in 17.1.3, 16.4.1

## Suggested inspection (read-only)
- `python -m pip show neutron`: prints the installed version. Run with the environment that serves production active.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on neutron.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-hvm4-mc7m-22w4 (OSV record GHSA-hvm4-mc7m-22w4 lists affected ranges: PyPI neutron >=0 =17.0.0 <17.1.3 (fixed))
- Verified: https://github.com/advisories/GHSA-hvm4-mc7m-22w4 (GitHub-reviewed advisory GHSA-hvm4-mc7m-22w4 lists affected ranges: PyPI neutron >=0 =17.0.0 =18.0.0 <=18.0.0)

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