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Fencer Vulns
critical 9.1

CVE-2021-38598 json

OpenStack Neutron vulnerable to hardware address impersonation

published 2021-08-23 5 y ago modified 2026-06-17 4 mo ago also GHSA-hvm4-mc7m-22w4 , PYSEC-2021-360 , EUVD-2021-0144

cvss
9.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.2%
EPSS 1.2% chance of exploitation in 30 days, percentile 68%
public exploits
0
none known

Summary

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.

Patch / fix

  • pypi neutron 16.4.1, 17.1.3, 18.1.0
  • openstack neutron 16.4.1, 17.1.3
  • neutron Debian 14, Debian 13, Debian 12 2:18.1.0-2

debian advisories DEBIAN-CVE-2021-38598

  • neutron Ubuntu 18.04 LTS 2:12.1.1-0ubuntu8.1
  • neutron Ubuntu 20.04 LTS 2:16.4.2-0ubuntu6.2

ubuntu advisories UBUNTU-CVE-2021-38598

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-38598 updated cvss 5.9

openstack-neutron: Linuxbridge ARP filter bypass on Netfilter platforms

  • Red Hat OpenStack Platform 17.1 python3-neutron, openstack-neutron, openstack-neutron-ml2, openstack-neutron-common, openstack-neutron-rpc-server, openstack-neutron-linuxbridge, +6 more
    affected: no fix planned “Out of support scope”
  • Red Hat OpenStack Platform 18.0 openstack-neutron
    affected: no fix available “Fix deferred”
  • Red Hat OpenStack Platform 10 (Newton) python-neutron, openstack-neutron, python-neutron-tests, openstack-neutron-ml2, openstack-neutron-common, openstack-neutron-rpc-server, +5 more Red Hat OpenStack Platform 13 (Queens) python-neutron, openstack-neutron, openstack-neutron-ml2, openstack-neutron-common, openstack-neutron-rpc-server, openstack-neutron-linuxbridge, +4 more Red Hat OpenStack Platform 16.1 python3-neutron, openstack-neutron, openstack-neutron-ml2, openstack-neutron-common, openstack-neutron-rpc-server, openstack-neutron-linuxbridge, +4 more Red Hat OpenStack Platform 16.2 python3-neutron, openstack-neutron, openstack-neutron-ml2, openstack-neutron-common, openstack-neutron-rpc-server, openstack-neutron-linuxbridge, +4 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.22% chance of exploitation in the next 30 days, higher than 68% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • launchpad.net https://launchpad.net/bugs/1938670 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
NVD 2.0 5.8 AV:N/AC:M/Au:N/C:N/I:P/A:P
GitHub 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

Affected packages

ecosystem package affected fixed in
pypi neutron
<16.4.1
>=17.0.0, <17.1.3
1 listed version
>=18.0.0, <18.1.0
16.4.1
17.1.3
18.1.0

Classification

Weakness
  • CWE-290 Authentication Bypass by Spoofing
  • CWE-863 Incorrect Authorization

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.