CVE-2019-16764 is a medium-severity (CVSS 5.5) Uncontrolled Resource Consumption vulnerability in pow_assent. A fix is available for pow_assent — see the affected versions and patch details below.
Denial of service
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-2019-16764 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
pow_assentReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Hex packages — download data is not available via public APIs for these ecosystems.
Description
The use of String.to_atom/1 in PowAssent is susceptible to denial of service attacks. In PowAssent.Phoenix.AuthorizationController a value is fetched from the user provided params, and String.to_atom/1 is used to convert the binary value to an atom so it can be used to fetch the provider configuration value. This is unsafe as it is user provided data, and can be used to fill up the whole atom table of ~1M which will cause the app to crash.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💧Hex | pow_assent | all versions | 0.4.4mix deps.update pow_assent |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pow_assent, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update pow_assent to 0.4.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2019-16764 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-2019-16764 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2019-16764. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2019-16764 in your dependencies?
O3 Security finds CVE-2019-16764 across Hex dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.