# CVE-2021-40085: OpenStack Neutron vulnerable to authenticated attackers reconfiguring dnsmasq via crafted extra_dhcp_opts value > Authenticated attackers can execute arbitrary commands by injecting malicious values into DHCP options, potentially compromising the network infrastructure. - **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N`) - **Exploited in the wild:** Not known - **Login needed:** Any signed-in user - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 31 Aug 2021 - **Updated:** 4 Aug 2024 - **Also known as:** DEBIAN-CVE-2021-40085, DLA-3027-1, DSA-4983-1, GHSA-fh73-gjvg-349c, PYSEC-2021-361, RHSA-2021:3481, RHSA-2021:3488, RHSA-2021:3502, RHSA-2021:3503, UBUNTU-CVE-2021-40085 ## What is CVE-2021-40085? CVE-2021-40085 is a medium-severity command injection vulnerability in Debian Debian Linux, published on 31 Aug 2021. Any signed-in user can exploit it over the network, with no action from the victim. ### Official description 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. ## Which versions are affected by CVE-2021-40085? 7 open source packages ship an affected version, including neutron. It affects 2 products. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `neutron` | PyPI | All versions | 16.4.1, 17.2.1, 18.1.1 | | `neutron` | PyPI | All versions | 16.4.1 | | `neutron` | PyPI | All versions | 16.4.1 | | `neutron` | PyPI | From 17.0.0 | 17.2.1 | | `neutron` | PyPI | From 17.0.0 | 17.2.1 | | `neutron` | PyPI | From 18.0.0 | 18.1.1 | | `neutron` | PyPI | From 18.0.0 | 18.1.1 | | `openstack-neutron` | Red Hat:openstack:10::el7 | All versions | 1:9.4.1-56.el7ost | | `openstack-neutron-common` | Red Hat:openstack:10::el7 | All versions | 1:9.4.1-56.el7ost | | `openstack-neutron-linuxbridge` | Red Hat:openstack:10::el7 | All versions | 1:9.4.1-56.el7ost | | `openstack-neutron-macvtap-agent` | Red Hat:openstack:10::el7 | All versions | 1:9.4.1-56.el7ost | | `openstack-neutron-metering-agent` | Red Hat:openstack:10::el7 | All versions | 1:9.4.1-56.el7ost | | `openstack-neutron-ml2` | Red Hat:openstack:10::el7 | All versions | 1:9.4.1-56.el7ost | | `openstack-neutron-openvswitch` | Red Hat:openstack:10::el7 | All versions | 1:9.4.1-56.el7ost | | `openstack-neutron-rpc-server` | Red Hat:openstack:10::el7 | All versions | 1:9.4.1-56.el7ost | | `openstack-neutron-sriov-nic-agent` | Red Hat:openstack:10::el7 | All versions | 1:9.4.1-56.el7ost | | `python-neutron` | Red Hat:openstack:10::el7 | All versions | 1:9.4.1-56.el7ost | | `python-neutron-tests` | Red Hat:openstack:10::el7 | All versions | 1:9.4.1-56.el7ost | | `openstack-neutron` | Red Hat:openstack:13::el7 | All versions | 1:12.1.1-42.1.el7ost | | `openstack-neutron-common` | Red Hat:openstack:13::el7 | All versions | 1:12.1.1-42.1.el7ost | | `openstack-neutron-linuxbridge` | Red Hat:openstack:13::el7 | All versions | 1:12.1.1-42.1.el7ost | | `openstack-neutron-macvtap-agent` | Red Hat:openstack:13::el7 | All versions | 1:12.1.1-42.1.el7ost | | `openstack-neutron-metering-agent` | Red Hat:openstack:13::el7 | All versions | 1:12.1.1-42.1.el7ost | | `openstack-neutron-ml2` | Red Hat:openstack:13::el7 | All versions | 1:12.1.1-42.1.el7ost | | `openstack-neutron-openvswitch` | Red Hat:openstack:13::el7 | All versions | 1:12.1.1-42.1.el7ost | | `openstack-neutron-rpc-server` | Red Hat:openstack:13::el7 | All versions | 1:12.1.1-42.1.el7ost | | `openstack-neutron-sriov-nic-agent` | Red Hat:openstack:13::el7 | All versions | 1:12.1.1-42.1.el7ost | | `python-neutron` | Red Hat:openstack:13::el7 | All versions | 1:12.1.1-42.1.el7ost | | `openstack-neutron` | Red Hat:openstack:16.1::el8 | All versions | 1:15.2.1-1.20210409073447.el8ost | | `openstack-neutron-common` | Red Hat:openstack:16.1::el8 | All versions | 1:15.2.1-1.20210409073447.el8ost | | `openstack-neutron-linuxbridge` | Red Hat:openstack:16.1::el8 | All versions | 1:15.2.1-1.20210409073447.el8ost | | `openstack-neutron-macvtap-agent` | Red Hat:openstack:16.1::el8 | All versions | 1:15.2.1-1.20210409073447.el8ost | | `openstack-neutron-metering-agent` | Red Hat:openstack:16.1::el8 | All versions | 1:15.2.1-1.20210409073447.el8ost | | `openstack-neutron-ml2` | Red Hat:openstack:16.1::el8 | All versions | 1:15.2.1-1.20210409073447.el8ost | | `openstack-neutron-openvswitch` | Red Hat:openstack:16.1::el8 | All versions | 1:15.2.1-1.20210409073447.el8ost | | `openstack-neutron-rpc-server` | Red Hat:openstack:16.1::el8 | All versions | 1:15.2.1-1.20210409073447.el8ost | | `openstack-neutron-sriov-nic-agent` | Red Hat:openstack:16.1::el8 | All versions | 1:15.2.1-1.20210409073447.el8ost | | `python3-neutron` | Red Hat:openstack:16.1::el8 | All versions | 1:15.2.1-1.20210409073447.el8ost | | `openstack-neutron` | Red Hat:openstack:16.2::el8 | All versions | 1:15.3.5-2.20210608154813.el8ost.3 | | `openstack-neutron-common` | Red Hat:openstack:16.2::el8 | All versions | 1:15.3.5-2.20210608154813.el8ost.3 | Products: Debian Debian Linux, Openstack Neutron. ## How do I fix CVE-2021-40085? Upgrade neutron to a fixed version for your release line: 16.4.1, 17.2.1 or 18.1.1. ## Is CVE-2021-40085 being exploited? There is no known exploitation of CVE-2021-40085 in the wild and no public exploit code. ## Other vulnerabilities in Debian Debian Linux - [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild) - [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild) - [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild) - [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild) - [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2021-40085 and fix it if it is affected. What it is: CVE-2021-40085 is a medium-severity command injection vulnerability in Debian Debian Linux, published on 31 Aug 2021. Any signed-in user can exploit it over the network, with no action from the victim. Exploitation: There is no known exploitation of CVE-2021-40085 in the wild and no public exploit code. Affected packages and fixed versions: - neutron (PyPI): affected all versions; fixed in 16.4.1, 17.2.1, 18.1.1 - neutron (PyPI): affected all versions; fixed in 16.4.1 - neutron (PyPI): affected all versions; fixed in 16.4.1 - neutron (PyPI): affected from 17.0.0; fixed in 17.2.1 - neutron (PyPI): affected from 17.0.0; fixed in 17.2.1 - neutron (PyPI): affected from 18.0.0; fixed in 18.1.1 - neutron (PyPI): affected from 18.0.0; fixed in 18.1.1 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2021-40085/ (Markdown: https://insights.sbomify.com/CVE-2021-40085/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2021-40085 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-40085 - OSV: https://osv.dev/vulnerability/CVE-2021-40085 --- From sbomify Insights: https://insights.sbomify.com/CVE-2021-40085/ Summaries are generated and may contain mistakes; the official description above is the record.