CVE-2017-16239 is a medium-severity (CVSS 6.5) vulnerability in nova. A fix is available for nova — see the affected versions and patch details below.
OpenStack Nova Filter Scheduler Bypass
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2017-16239 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,333 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
nova🐍nova🐍novaReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
In OpenStack Nova through 14.0.9, 15.x through 15.0.7, and 16.x through 16.0.2, by rebuilding an instance, an authenticated user may be able to circumvent the Filter Scheduler bypassing imposed filters (for example, the ImagePropertiesFilter or the IsolatedHostsFilter). All setups using Nova Filter Scheduler are affected. Because of the regression described in Launchpad Bug #1732947, the preferred fix is a 14.x version after 14.0.10, a 15.x version after 15.0.8, or a 16.x version after 16.0.3.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | nova | ≥ 16.0.0&&< 16.0.3 | 16.0.3pip install --upgrade 'nova==16.0.3' |
| 🐍PyPI | nova | ≥ 15.0.0&&< 15.0.8 | 15.0.8pip install --upgrade 'nova==15.0.8' |
| 🐍PyPI | nova | ≥ 14.0.0&&< 14.0.10 | 14.0.10pip install --upgrade 'nova==14.0.10' |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for nova, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update nova to 16.0.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2017-16239 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2017-16239 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2017-16239. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
The upstream fix requires RequestSpec, which was introduced in OSP10. Patching versions, prior to version 10, comes with a considerable risk of introducing new bugs. Based on the impact of this vulnerability it was determined that OSP6 to 9 would not be fixed.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat OpenStack Platform 10.0 (Newton) | openstack-nova-1:14.1.0-3.el7ost | RHSA-2018:0369 |
| Red Hat OpenStack Platform 11.0 (Ocata) | openstack-nova-1:15.0.8-5.el7ost | RHSA-2018:0314 |
| Red Hat OpenStack Platform 12.0 (Pike) | openstack-nova-1:16.0.2-9.el7ost | RHSA-2018:0241 |
Frequently Asked Questions
Is CVE-2017-16239 in your dependencies?
O3 Security finds CVE-2017-16239 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.