CVE-2018-17175 is a medium-severity (CVSS 5.3) vulnerability in marshmallow. O3 Security confirms whether CVE-2018-17175 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
In marshmallow library the schema "only" option treats an empty list as implying no "only" option
Real-World Exposure
marshmallow🐍marshmallowReal-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 the marshmallow library before 2.15.1 and 3.x before 3.0.0b9 for Python, the schema "only" option treats an empty list as implying no "only" option, which allows a request that was intended to expose no fields to instead expose all fields (if the schema is being filtered dynamically using the "only" option, and there is a user role that produces an empty value for "only").
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | marshmallow | all versions | 2.15.1 |
| 🐍PyPI | marshmallow | ≥ 3.0a0&&< 3.0.0b9 | 3.0.0b9 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for marshmallow. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update marshmallow to 2.15.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2018-17175 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 pinpoints whether CVE-2018-17175 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2018-17175. 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-2018-17175 in your dependencies?
O3 detects CVE-2018-17175 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.