GHSA-428g-f7cq-pgp5 is a medium-severity (CVSS 5.3) CWE-405 vulnerability in marshmallow. A fix is available for marshmallow — see the affected versions and patch details below.
Marshmallow has DoS in Schema.load(many)
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-428g-f7cq-pgp5.
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-428g-f7cq-pgp5 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 379,145 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
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
Impact
Schema.load(data, many=True) is vulnerable to denial of service attacks. A moderately sized request can consume a disproportionate amount of CPU time.
Patches
4.1.2, 3.26.2
Workarounds
# Fail fast
def load_many(schema, data, **kwargs):
if not isinstance(data, list):
raise ValidationError(['Invalid input type.'])
return [schema.load(item, **kwargs) for item in data]
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | marshmallow | ≥ 3.0.0rc1&&< 3.26.2 | 3.26.2pip install --upgrade 'marshmallow==3.26.2' |
| 🐍PyPI | marshmallow | ≥ 4.0.0&&< 4.1.2 | 4.1.2pip install --upgrade 'marshmallow==4.1.2' |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for marshmallow, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update marshmallow to 3.26.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-428g-f7cq-pgp5 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-428g-f7cq-pgp5 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-428g-f7cq-pgp5. 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-428g-f7cq-pgp5 in your dependencies?
O3 Security finds GHSA-428g-f7cq-pgp5 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.