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Fencer Vulns
medium 6.5

CVE-2021-40797 json

OpenStack Neutron Denial of Service vulnerability

published 2021-09-08 5 y ago modified 2026-06-17 4 mo ago also GHSA-cpx3-696p-3cw9 , PYSEC-2021-329 , EUVD-2021-0143

cvss
6.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.8%
EPSS 1.8% chance of exploitation in 30 days, percentile 78%
public exploits
0
none known

Summary

An issue was discovered in the routes middleware in OpenStack Neutron before 16.4.1, 17.x before 17.2.1, and 18.x before 18.1.1. By making API requests involving nonexistent controllers, an authenticated user may cause the API worker to consume increasing amounts of memory, resulting in API performance degradation or denial of service.

Patch / fix

  • pypi neutron 16.4.1, 17.2.1, 18.1.1
  • openstack neutron 16.4.1, 17.2.1, 18.1.1
  • neutron Debian 14, Debian 13, Debian 12 2:19.0.0-1

debian advisories DEBIAN-CVE-2021-40797

  • 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-2021-40797

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

  • python3-neutron openstack 16.1 1:15.2.1-1.20220112133420.el8ost
  • openstack-neutron openstack 16.1 1:15.2.1-1.20220112133420.el8ost
  • openstack-neutron-ml2 openstack 16.1 1:15.2.1-1.20220112133420.el8ost
  • openstack-neutron-common openstack 16.1 1:15.2.1-1.20220112133420.el8ost
  • openstack-neutron-rpc-server openstack 16.1 1:15.2.1-1.20220112133420.el8ost
  • openstack-neutron-linuxbridge openstack 16.1 1:15.2.1-1.20220112133420.el8ost
  • openstack-neutron-openvswitch openstack 16.1 1:15.2.1-1.20220112133420.el8ost
  • openstack-neutron-macvtap-agent openstack 16.1 1:15.2.1-1.20220112133420.el8ost

red hat advisories RHSA-2022:0990RHSA-2022:0996

  • openstack-neutron OpenStack Cloud Crowbar 8, OpenStack Cloud 8, HPE Helion OpenStack 8 11.0.9~dev69-3.43.1

suse advisories SUSE-SU-2022:1884-1

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-2021-40797 updated cvss 6.5

openstack-neutron: Routes middleware memory leak for nonexistent controllers

  • 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 17.1 python3-neutron, openstack-neutron, openstack-neutron-ml2, openstack-neutron-common, openstack-neutron-rpc-server, openstack-neutron-linuxbridge, +6 more
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat OpenStack Platform 18.0 openstack-neutron
    affected: workaround, no fix available “Fix deferred”
  • Red Hat OpenStack Platform 16.1 python3-neutron 15.2.1-1.20220112133420.el8ost, openstack-neutron 15.2.1-1.20220112133420.el8ost, openstack-neutron-ml2 15.2.1-1.20220112133420.el8ost, openstack-neutron-common 15.2.1-1.20220112133420.el8ost, openstack-neutron-rpc-server 15.2.1-1.20220112133420.el8ost, openstack-neutron-linuxbridge 15.2.1-1.20220112133420.el8ost, +4 more
    fixed: vendor fix RHSA-2022:0990
  • Red Hat OpenStack Platform 16.2 python3-neutron 15.3.5-2.20220113150031.el8ost, openstack-neutron 15.3.5-2.20220113150031.el8ost, openstack-neutron-ml2 15.3.5-2.20220113150031.el8ost, openstack-neutron-common 15.3.5-2.20220113150031.el8ost, openstack-neutron-rpc-server 15.3.5-2.20220113150031.el8ost, openstack-neutron-linuxbridge 15.3.5-2.20220113150031.el8ost, +4 more
    fixed: vendor fix RHSA-2022:0996
  • Red Hat Integration Camel K 1 openstack-neutron
    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

1.81% chance of exploitation in the next 30 days, higher than 78% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • launchpad.net https://launchpad.net/bugs/1942179 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 4.0 AV:N/AC:L/Au:S/C:N/I:N/A:P
GitHub 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
pypi neutron
<16.4.1
>=17.0.0, <17.2.1
>=18.0.0, <18.1.1
16.4.1
17.2.1
18.1.1

Classification

Weakness
  • CWE-772 Missing Release of Resource after Effective Lifetime

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.