GHSA-4v9f-r55g-g6hc is a high-severity (CVSS 7.6) CWE-346 vulnerability in prefect. A fix is available for prefect — see the affected versions and patch details below.
Prefect CORS (Cross-Origin Resource Sharing) misconfiguration
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for GHSA-4v9f-r55g-g6hc.
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
GHSA-4v9f-r55g-g6hc 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 377,166 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
prefect🐍prefectReal-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 CORS (Cross-Origin Resource Sharing) misconfiguration in prefecthq/prefect prior to version 3.0.3 allows unauthorized domains to access sensitive data. This vulnerability can lead to unauthorized access to the database, resulting in potential data leaks, loss of confidentiality, service disruption, and data integrity risks.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | prefect | ≥ 3.0.0rc1&&< 3.0.3 | 3.0.3pip install --upgrade 'prefect==3.0.3' |
| 🐍PyPI | prefect | all versions | 2.20.17pip install --upgrade 'prefect==2.20.17' |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for prefect, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update prefect to 3.0.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-4v9f-r55g-g6hc 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 GHSA-4v9f-r55g-g6hc can be triaged on real exposure rather than presence alone.
Tailored to GHSA-4v9f-r55g-g6hc. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-4v9f-r55g-g6hc in your dependencies?
O3 Security finds GHSA-4v9f-r55g-g6hc across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.