CVE-2020-17376 is a high-severity (CVSS 8.3) XML External Entity (XXE) vulnerability in nova. 1 public exploit reference exists, so weaponization risk is real. A fix is available for nova — see the affected versions and patch details below.
OpenStack Nova Live migration fails to update persistent domain XML
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-2020-17376 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 378,156 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
An issue was discovered in Guest.migrate in virt/libvirt/guest.py in OpenStack Nova before 19.3.1, 20.x before 20.3.1, and 21.0.0. By performing a soft reboot of an instance that has previously undergone live migration, a user may gain access to destination host devices that share the same paths as host devices previously referenced by the virtual machine on the source host. This can include block devices that map to different Cinder volumes at the destination than at the source. Only deployments allowing host-based connections (for instance, root and ephemeral devices) are affected.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | nova | all versions | 19.3.1pip install --upgrade 'nova==19.3.1' |
| 🐍PyPI | nova | ≥ 20.0.0&&< 20.3.1 | 20.3.1pip install --upgrade 'nova==20.3.1' |
| 🐍PyPI | nova | all versions | No fix |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
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 19.3.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-17376 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-2020-17376 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2020-17376. 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.
Red Hat OpenStack Platform 10 was initially marked as affected, however it has since been discovered that the flaw is actually not present in this version. For this reason, the update in RHSA-2020:3711 can be either applied or ignored for RHOSP 10.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat OpenStack Platform 10.0 (Newton) | openstack-nova-1:14.1.0-65.el7ost | RHSA-2020:3711 |
| Red Hat OpenStack Platform 13.0 (Queens) | openstack-nova-1:17.0.13-24.el7ost | RHSA-2020:3708 |
| Red Hat OpenStack Platform 15.0 (Stein) | openstack-nova-1:19.1.0-0.20200207070459.bf9d9e5.el8ost | RHSA-2020:3706 |
| Red Hat OpenStack Platform 16.0 (Train) | openstack-nova-1:20.1.2-0.20200401205215.28324e6.el8ost | RHSA-2020:3704 |
| Red Hat OpenStack Platform 16.1 | openstack-nova-1:20.3.1-0.20200626213436.38ee1f3.el8ost | RHSA-2020:3702 |
Frequently Asked Questions
Is CVE-2020-17376 in your dependencies?
O3 Security finds CVE-2020-17376 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.