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CVE-2021-40797

OpenStack Neutron Denial of Service vulnerability

6.5 MediumFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
Low
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

1.77%Up 1.3 points since Sep 9, 2021
90%50%10%1%

What each source reports

NVD Score used 6.5

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.

Record
CVE-2021-40797
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CVSS 2.0
4.0 MediumAV:N/AC:L/Au:S/C:N/I:N/A:P
Weakness
CWE-772
Updated
2026-11-02
CVE List No score

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.

Record
CVE-2021-40797
Updated
2026-11-02
EUVDEUVD-2021-0143 No score

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.

Record
EUVD-2021-0143
Updated
2026-11-03
GitHub AdvisoriesGHSA-cpx3-696p-3cw9 7.1

OpenStack Neutron Denial of Service vulnerability

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.

Record
GHSA-cpx3-696p-3cw9
CVSS 4.0
7.1 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-772
Updated
2026-11-02
OSV 6.5

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.

Record
CVE-2021-40797
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVDEBIAN-CVE-2021-40797 6.5

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.

Record
DEBIAN-CVE-2021-40797
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
Show 7 moreShow less
OSVGHSA-cpx3-696p-3cw9 7.1

OpenStack Neutron Denial of Service vulnerability

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.

Record
GHSA-cpx3-696p-3cw9
CVSS 4.0
7.1 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-772
Updated
2026-11-02
OSVRHSA-2022:0990 6.5

Red Hat Security Advisory: Red Hat OpenStack Platform 16.1 (openstack-neutron) security update

Record
RHSA-2022:0990
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVRHSA-2022:0996 6.5

Red Hat Security Advisory: Red Hat OpenStack Platform 16.2 (openstack-neutron) security update

Record
RHSA-2022:0996
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2021-40797 6.5

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.

Record
UBUNTU-CVE-2021-40797
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVPYSEC-2021-329 No score

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.

Record
PYSEC-2021-329
Updated
2026-11-02
OSVSUSE-SU-2022:1884-1 No score

Security update for openstack-neutron

This update for openstack-neutron fixes the following issues:

  • CVE-2021-40797: Fixed routes middleware memory leak for nonexistent controllers (bsc#1190339).
  • CVE-2021-40085: Fixed arbitrary dnsmasq reconfiguration via extra_dhcp_opts (bsc#1189794).
Record
SUSE-SU-2022:1884-1
Updated
2026-11-02
OSVUSN-6067-1 No score

neutron vulnerabilities

David Sinquin discovered that OpenStack Neutron incorrectly handled the default Open vSwitch firewall rules. An attacker could possibly use this issue to impersonate the IPv6 addresses of other systems on the network. This issue only affected Ubuntu 18.04 LTS, and Ubuntu 20.04 LTS. (CVE-2021-20267)

Jake Yip and Justin Mammarella discovered that OpenStack Neutron incorrectly handled the linuxbridge driver when ebtables-nft is being used. An attacker could possibly use this issue to impersonate the hardware addresss of other systems on the network. This issue only affected Ubuntu 18.04 LTS, and Ubuntu 20.04 LTS. (CVE-2021-38598)

Pavel Toporkov discovered that OpenStack Neutron incorrectly handled extra_dhcp_opts values. An attacker could possibly use this issue to reconfigure dnsmasq. This issue only affected Ubuntu 18.04 LTS, and Ubuntu 20.04 LTS. (CVE-2021-40085)

Slawek Kaplonski discovered that OpenStack Neutron incorrectly handled the routes middleware. An attacker could possibly use this issue to cause the API worker to consume memory, leading to a denial of service. This issue only affected Ubuntu 18.04 LTS, and Ubuntu 20.04 LTS. (CVE-2021-40797)

It was discovered that OpenStack Neutron incorrectly handled certain queries. A remote authenticated user could possibly use this issue to cause resource consumption, leading to a denial of service. (CVE-2022-3277)

Record
USN-6067-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
neutron
PyPI
before 16.4.1
16.4.1
neutron
PyPI
17.0.0 up to 17.2.1
17.2.1
neutron
PyPI
18.0.0 up to 18.1.1
18.1.1
neutron
Debian:12
before 2:19.0.0-1
2:19.0.0-1
neutron
Debian:13
before 2:19.0.0-1
2:19.0.0-1
neutron
Debian:14
before 2:19.0.0-1
2:19.0.0-1
neutron
PyPI
before 16.4.1, plus listed versions
0.010.0.510.0.610.0.711.0.3
Show 45 moreShow less
11.0.411.0.511.0.611.0.711.0.812.0.012.0.0.0b312.0.0.0rc112.0.0.0rc212.0.112.0.212.0.312.0.412.0.512.0.612.1.012.1.113.0.013.0.0.0b113.0.0.0b213.0.0.0b313.0.0.0rc113.0.0.0rc213.0.113.0.213.0.313.0.413.0.513.0.613.0.714.0.014.0.0.0b114.0.0.0b214.0.0.0b314.0.0.0rc114.0.114.0.214.0.314.0.414.1.014.2.014.3.014.3.114.4.014.4.1
16.4.1
neutron
PyPI
17.0.0 up to 17.2.1, plus listed versions
17.1.017.1.117.1.217.2.0
17.2.1
neutron
PyPI
18.0.0 up to 18.1.1, plus listed versions
18.1.0
18.1.1
neutron
PyPI
before 16.4.1, 17.0.0 up to 17.2.1, 18.0.0 up to 18.1.1, plus listed versions
0.010.0.510.0.610.0.711.0.3
Show 45 moreShow less
11.0.411.0.511.0.611.0.711.0.812.0.012.0.0.0b312.0.0.0rc112.0.0.0rc212.0.112.0.212.0.312.0.412.0.512.0.612.1.012.1.113.0.013.0.0.0b113.0.0.0b213.0.0.0b313.0.0.0rc113.0.0.0rc213.0.113.0.213.0.313.0.413.0.513.0.613.0.714.0.014.0.0.0b114.0.0.0b214.0.0.0b314.0.0.0rc114.0.114.0.214.0.314.0.414.1.014.2.014.3.014.3.114.4.014.4.1
16.4.117.2.118.1.1
Show 30 moreShow less
Affected packages
PackageAffectedFixed
openstack-neutron
Red Hat:openstack:16.1::el8
before 1:15.2.1-1.20220112133420.el8ost
1:15.2.1-1.20220112133420.el8ost
openstack-neutron-common
Red Hat:openstack:16.1::el8
before 1:15.2.1-1.20220112133420.el8ost
1:15.2.1-1.20220112133420.el8ost
openstack-neutron-linuxbridge
Red Hat:openstack:16.1::el8
before 1:15.2.1-1.20220112133420.el8ost
1:15.2.1-1.20220112133420.el8ost
openstack-neutron-macvtap-agent
Red Hat:openstack:16.1::el8
before 1:15.2.1-1.20220112133420.el8ost
1:15.2.1-1.20220112133420.el8ost
openstack-neutron-metering-agent
Red Hat:openstack:16.1::el8
before 1:15.2.1-1.20220112133420.el8ost
1:15.2.1-1.20220112133420.el8ost
openstack-neutron-ml2
Red Hat:openstack:16.1::el8
before 1:15.2.1-1.20220112133420.el8ost
1:15.2.1-1.20220112133420.el8ost
openstack-neutron-openvswitch
Red Hat:openstack:16.1::el8
before 1:15.2.1-1.20220112133420.el8ost
1:15.2.1-1.20220112133420.el8ost
openstack-neutron-rpc-server
Red Hat:openstack:16.1::el8
before 1:15.2.1-1.20220112133420.el8ost
1:15.2.1-1.20220112133420.el8ost
openstack-neutron-sriov-nic-agent
Red Hat:openstack:16.1::el8
before 1:15.2.1-1.20220112133420.el8ost
1:15.2.1-1.20220112133420.el8ost
python3-neutron
Red Hat:openstack:16.1::el8
before 1:15.2.1-1.20220112133420.el8ost
1:15.2.1-1.20220112133420.el8ost
openstack-neutron
Red Hat:openstack:16.2::el8
before 1:15.3.5-2.20220113150031.el8ost
1:15.3.5-2.20220113150031.el8ost
openstack-neutron-common
Red Hat:openstack:16.2::el8
before 1:15.3.5-2.20220113150031.el8ost
1:15.3.5-2.20220113150031.el8ost
openstack-neutron-linuxbridge
Red Hat:openstack:16.2::el8
before 1:15.3.5-2.20220113150031.el8ost
1:15.3.5-2.20220113150031.el8ost
openstack-neutron-macvtap-agent
Red Hat:openstack:16.2::el8
before 1:15.3.5-2.20220113150031.el8ost
1:15.3.5-2.20220113150031.el8ost
openstack-neutron-metering-agent
Red Hat:openstack:16.2::el8
before 1:15.3.5-2.20220113150031.el8ost
1:15.3.5-2.20220113150031.el8ost
openstack-neutron-ml2
Red Hat:openstack:16.2::el8
before 1:15.3.5-2.20220113150031.el8ost
1:15.3.5-2.20220113150031.el8ost
openstack-neutron-openvswitch
Red Hat:openstack:16.2::el8
before 1:15.3.5-2.20220113150031.el8ost
1:15.3.5-2.20220113150031.el8ost
openstack-neutron-rpc-server
Red Hat:openstack:16.2::el8
before 1:15.3.5-2.20220113150031.el8ost
1:15.3.5-2.20220113150031.el8ost
openstack-neutron-sriov-nic-agent
Red Hat:openstack:16.2::el8
before 1:15.3.5-2.20220113150031.el8ost
1:15.3.5-2.20220113150031.el8ost
python3-neutron
Red Hat:openstack:16.2::el8
before 1:15.3.5-2.20220113150031.el8ost
1:15.3.5-2.20220113150031.el8ost
openstack-neutron
SUSE:HPE Helion OpenStack 8
before 11.0.9~dev69-3.43.1
11.0.9~dev69-3.43.1
openstack-neutron-doc
SUSE:HPE Helion OpenStack 8
before 11.0.9~dev69-3.43.1
11.0.9~dev69-3.43.1
openstack-neutron
SUSE:OpenStack Cloud 8
before 11.0.9~dev69-3.43.1
11.0.9~dev69-3.43.1
openstack-neutron-doc
SUSE:OpenStack Cloud 8
before 11.0.9~dev69-3.43.1
11.0.9~dev69-3.43.1
openstack-neutron
SUSE:OpenStack Cloud Crowbar 8
before 11.0.9~dev69-3.43.1
11.0.9~dev69-3.43.1
openstack-neutron-doc
SUSE:OpenStack Cloud Crowbar 8
before 11.0.9~dev69-3.43.1
11.0.9~dev69-3.43.1
neutron
Ubuntu:16.04:LTS
All versions, plus listed versions
2:7.0.0-0ubuntu12:8.0.0~b1-0ubuntu22:8.0.0~b2-0ubuntu42:8.0.0~b2-0ubuntu52:8.0.0~b2-0ubuntu7
Show 20 moreShow less
2:8.0.0~b3-0ubuntu12:8.0.0~rc1-0ubuntu12:8.0.0-0ubuntu12:8.1.0-0ubuntu0.16.04.22:8.1.2-0ubuntu12:8.2.0-0ubuntu12:8.3.0-0ubuntu12:8.3.0-0ubuntu1.12:8.3.0-0ubuntu1.22:8.4.0-0ubuntu12:8.4.0-0ubuntu22:8.4.0-0ubuntu32:8.4.0-0ubuntu42:8.4.0-0ubuntu52:8.4.0-0ubuntu62:8.4.0-0ubuntu7.12:8.4.0-0ubuntu7.22:8.4.0-0ubuntu7.32:8.4.0-0ubuntu7.42:8.4.0-0ubuntu7.5
None known
neutron
Ubuntu:18.04:LTS
before 2:12.1.1-0ubuntu8.1, plus listed versions
2:11.0.1-0ubuntu12:12.0.0~b1-0ubuntu12:12.0.0~b1-0ubuntu22:12.0.0~b2-0ubuntu12:12.0.0~b3-0ubuntu1
Show 26 moreShow less
2:12.0.0~rc1-0ubuntu12:12.0.0~rc2-0ubuntu12:12.0.0-0ubuntu12:12.0.0-0ubuntu1.12:12.0.0-0ubuntu1.22:12.0.0-0ubuntu1.32:12.0.0-0ubuntu1.42:12.0.0-0ubuntu22:12.0.0-0ubuntu32:12.0.1-0ubuntu12:12.0.1-0ubuntu1.12:12.0.2-0ubuntu12:12.0.3-0ubuntu12:12.0.5-0ubuntu12:12.0.5-0ubuntu42:12.0.5-0ubuntu52:12.0.6-0ubuntu12:12.0.6-0ubuntu22:12.0.6-0ubuntu32:12.1.0-0ubuntu12:12.1.1-0ubuntu12:12.1.1-0ubuntu22:12.1.1-0ubuntu32:12.1.1-0ubuntu42:12.1.1-0ubuntu72:12.1.1-0ubuntu8
2:12.1.1-0ubuntu8.1
neutron
Ubuntu:20.04:LTS
before 2:16.4.2-0ubuntu6.2, plus listed versions
2:15.0.0-0ubuntu12:16.0.0~b1~git2019121613.3e8abb9a8f-0ubuntu12:16.0.0~b2~git2020020712.d5b33ffc77-0ubuntu12:16.0.0~b2~git2020020712.d5b33ffc77-0ubuntu32:16.0.0~b3~git2020032420.a0e1b5804e-0ubuntu1
Show 28 moreShow less
2:16.0.0~b3~git2020032420.a0e1b5804e-0ubuntu22:16.0.0~b3~git2020032420.a0e1b5804e-0ubuntu32:16.0.0~b3~git2020032420.a0e1b5804e-0ubuntu42:16.0.0~b3~git2020041013.e74c8f8c88-0ubuntu12:16.0.0~b3~git2020041516.5f42488a9a-0ubuntu12:16.0.0~b3~git2020041516.5f42488a9a-0ubuntu22:16.0.0-0ubuntu0.20.04.12:16.0.0-0ubuntu0.20.04.22:16.1.0-0ubuntu12:16.1.0-0ubuntu22:16.2.0-0ubuntu12:16.2.0-0ubuntu22:16.2.0-0ubuntu32:16.3.0-0ubuntu32:16.3.1-0ubuntu12:16.3.1-0ubuntu1.12:16.3.2-0ubuntu22:16.3.2-0ubuntu32:16.4.0-0ubuntu22:16.4.0-0ubuntu32:16.4.1-0ubuntu22:16.4.2-0ubuntu12:16.4.2-0ubuntu22:16.4.2-0ubuntu32:16.4.2-0ubuntu42:16.4.2-0ubuntu52:16.4.2-0ubuntu62:16.4.2-0ubuntu6.1
2:16.4.2-0ubuntu6.2
neutron
Ubuntu:22.04:LTS
before 2:20.3.0-0ubuntu1.1, plus listed versions
2:19.0.0-0ubuntu12:19.1.0+git2022030313.b072cbf05f-0ubuntu12:20.0.0-0ubuntu12:20.0.0-0ubuntu22:20.0.0-0ubuntu32:20.1.0-0ubuntu22:20.2.0-0ubuntu12:20.3.0-0ubuntu1
2:20.3.0-0ubuntu1.1

History

History
RecordedChangedSources
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-40797 is a medium vulnerability (CVSS 6.5) in Openstack Neutron, published September 8, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.77%, the 78th percentile. Fixed in neutron 16.4.1.

References

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This page doesn't list everything

Left out here: 53 versions. The JSON record has them.

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