CVE-2021-3654 — nova
MEDIUMCVE-2021-3654 is a medium-severity (CVSS 6.1) Open Redirect 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.
Open Redirect in CPython that affects users of OpenStack Nova
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2021-3654 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 386,684 CVEs with a current EPSS score, this one falls in the 10–50% band (highlighted). Counts from FIRST.org, log-scaled.
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
A vulnerability was found in CPython which is used by openstack-nova's console proxy, noVNC. By crafting a malicious URL, noVNC could be made to redirect to any desired URL.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | nova | all versions | 21.2.3pip install --upgrade 'nova==21.2.3' |
| 🐍PyPI | nova | ≥ 22.0.0&&< 22.2.3 | 22.2.3pip install --upgrade 'nova==22.2.3' |
| 🐍PyPI | nova | ≥ 23.0.0&&< 23.0.3 | 23.0.3pip install --upgrade 'nova==23.0.3' |
Affected Products
novaopenstackopenstack platformredhatResearch 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 21.2.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-3654 is resolved across your whole dependency graph.
Workarounds
Stop reflecting attacker-controlled destinations: resolve every redirect target against an allowlist of paths or hosts you own, prefer a server-side key over a full URL in the request, and reject absolute URLs entirely where the flow only ever needs a relative one.
How to detect CVE-2021-3654
A community-maintained Nuclei template exists for this CVE. You can scan for it directly:
nuclei -id cve-2021-3654 -u https://target- Template
- Nova noVNC - Open Redirect
- Severity
- medium
- Impact
- An attacker can exploit this vulnerability to redirect users to malicious websites, leading to potential phishing attacks.
- Remediation
- Apply the latest security patches or updates provided by the vendor to fix the open redirect vulnerability in the Nova noVNC application.
Template by ProjectDiscovery nuclei-templates (geeknik), MIT licensed. View the full template. Scan only systems you are authorised to test.
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.
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.Source: Red Hat security advisory for CVE-2021-3654 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat OpenStack Platform 16.1 | openstack-nova-1:20.4.1-1.20220112153422.1ee93b9.el8ost | RHSA-2022:0983 |
| Red Hat OpenStack Platform 16.2 | openstack-nova-1:20.6.2-2.20220112164912.8906554.el8ost | RHSA-2022:0999 |
Frequently Asked Questions
Is CVE-2021-3654 in your dependencies?
Find it across PyPI, including transitive dependencies.