CVE-2021-40085

MEDIUMNVD 6.56.5—

6.5

An issue was discovered in OpenStack Neutron before 16.4.1, 17.x before 17.2.1, and 18.x before 18.1.1. Authenticated attackers can reconfigure dnsmasq via a crafted extra_dhcp_opts value.

CVSS v3: 6.5
EG Score: 6.5(medium)
EPSS: 80.4%
KEV: Not listed

Published

August 31, 2021

Last Modified

November 21, 2024

References (12)

cve@mitrehttp://www.openwall.com/lists/oss-security/2021/08/31/2
cve@mitrehttps://launchpad.net/bugs/1939733
cve@mitrehttps://lists.debian.org/debian-lts-announce/2021/10/msg00005.html
cve@mitrehttps://lists.debian.org/debian-lts-announce/2022/05/msg00038.html
cve@mitrehttps://security.openstack.org/ossa/OSSA-2021-005.html
cve@mitrehttps://www.debian.org/security/2021/dsa-4983
af854a3a-2127-422b-91ae-364da2661108http://www.openwall.com/lists/oss-security/2021/08/31/2
af854a3a-2127-422b-91ae-364da2661108https://launchpad.net/bugs/1939733
af854a3a-2127-422b-91ae-364da2661108https://lists.debian.org/debian-lts-announce/2021/10/msg00005.html
af854a3a-2127-422b-91ae-364da2661108https://lists.debian.org/debian-lts-announce/2022/05/msg00038.html
af854a3a-2127-422b-91ae-364da2661108https://security.openstack.org/ossa/OSSA-2021-005.html
af854a3a-2127-422b-91ae-364da2661108https://www.debian.org/security/2021/dsa-4983

Patch Availability(5)

Vendor / Ecosystem	Fixed in / Patch	Released	Source
ubuntu	neutron-macvtap-agent (2:20.3.0-0ubuntu1.1) @ jammy	2026-05-26	ubuntu
redhat	openstack-neutron-1:15.3.5-2.20210608154813.el8ost.3	2021-09-15	redhat
redhat	openstack-neutron-1:12.1.1-42.1.el7ost	2021-09-13	redhat
redhat	openstack-neutron-1:9.4.1-56.el7ost	2021-09-13	redhat
redhat	openstack-neutron-1:15.2.1-1.20210409073447.el8ost	2021-09-09	redhat

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)

Package	Vulnerable range	Fixed in	Dependents
neutron	0.0 ... 18.1.0 (81 versions)	18.1.1	—

All Vendor Advisories

(5)

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 11× in last 7d / 20× in last 30d)

Every time one of our enrichment pipelines (NVD, MITRE cvelistV5, EPSS, CISA KEV, GHSA, OSV, vendor advisories) ran against this CVE. Most recent first.

2026-06-02 20:11 UTCepss_batch
2026-06-02 20:11 UTCepss_batch
2026-06-01 13:50 UTCepss_batch
2026-06-01 13:50 UTCepss_batch
2026-05-31 22:29 UTCepss_batch
2026-05-31 22:29 UTCepss_batch
2026-05-31 00:15 UTCepss_batch
2026-05-31 00:15 UTCepss_batch
2026-05-29 13:42 UTCepss_batch
2026-05-28 13:43 UTCepss_batch
2026-05-28 13:43 UTCepss_batch
2026-05-27 13:39 UTCepss_batch
2026-05-27 13:39 UTCepss_batch
2026-05-26 13:42 UTCepss_batch
2026-05-26 13:42 UTCepss_batch
2026-05-26 11:13 UTCEG score recompute
2026-05-26 11:13 UTCVendor advisory
2026-05-26 07:17 UTCepss_batch
2026-05-26 07:17 UTCepss_batch
2026-05-26 07:17 UTCepss_batch

Frequently asked(5)

What is CVE-2021-40085?

CVE-2021-40085 is a medium vulnerability published on August 31, 2021. An issue was discovered in OpenStack Neutron before 16.4.1, 17.x before 17.2.1, and 18.x before 18.1.1. Authenticated attackers can reconfigure dnsmasq via a crafted extradhcpopts value.

When was CVE-2021-40085 disclosed?

CVE-2021-40085 was first published in the National Vulnerability Database on August 31, 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-2021-40085 actively exploited?

CVE-2021-40085 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 80.4% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

What is the CVSS score of CVE-2021-40085?

CVE-2021-40085 has a CVSS v3 base score of 6.5 (NVD).

How do I remediate CVE-2021-40085?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-40085, 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.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2021-40085

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