CVE-2021-40085

Exp

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.

Published: 2021-08-31 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-40085 is rated High Exploit Risk (68/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 1.89%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2021-40085

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2021-40085

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-24 1.76% 1.89% +0.13%
2 2026-06-15 1.35% 1.76% +0.41%
3 2026-05-15 — 1.35% —

Full EPSS history (22 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-40085

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 3.6 [email protected]
4.0 2.0 MEDIUM
AV:N/AC:L/Au:S/C:N/I:P/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:S)
A single authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 8.0 2.9 [email protected]

Weakness enumeration for CVE-2021-40085

GitHub Security Advisory for CVE-2021-40085

GHSA-fh73-gjvg-349c · Severity: high · Ecosystem: pip — OpenStack Neutron vulnerable to authenticated attackers reconfiguring dnsmasq via crafted extra_dhcp_opts value

OS Trackers for CVE-2021-40085

vendor priority summary link
debian not yet assigned CVE-2021-40085 not yet assigned priority: Debian including 1 source packages (neutron), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-40085
redhat high — https://access.redhat.com/security/cve/CVE-2021-40085
suse high CVE-2021-40085 severity important: SUSE including 71 source package names (ardana-barbican-9.0+git.1644879908.8a641c1-3.13.1, grafana-6.7.4-3.26.1, …), 135 product×package rows across 5 product lines (HPE Helion OpenStack 8, SUSE OpenStack Cloud 8, … (5 product lines)): Fixed 135. https://www.suse.com/security/cve/CVE-2021-40085/
ubuntu medium CVE-2021-40085 medium priority: Ubuntu including 1 source packages (neutron), 15 status rows across 15 suites (bionic, focal, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): not-affected 9, released 3, DNE 1, ignored 1, needs-triage 1. https://ubuntu.com/security/CVE-2021-40085

Affected software / configurations for CVE-2021-40085

Vendor Product Version Raw CPE
openstack neutron < 16.4.1 cpe:2.3:a:openstack:neutron:*:*:*:*:*:*:*:*
openstack neutron >= 17.0.0, < 17.2.1 cpe:2.3:a:openstack:neutron:*:*:*:*:*:*:*:*
openstack neutron >= 18.0.0, < 18.1.1 cpe:2.3:a:openstack:neutron:*:*:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
debian debian_linux 11.0 cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*

References for CVE-2021-40085

cvelogic Threat Intelligence