CVE-2022-21213 is a high-severity (CVSS 7.5) CWE-1321 vulnerability in mout. 5 public exploit or proof-of-concept references are indexed, so weaponization risk is real. A fix is available for mout — see the affected versions and patch details below.
Prototype Pollution in mout
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
moutnpmDescription
This affects all versions of package mout. The deepFillIn function can be used to 'fill missing properties recursively', while the deepMixIn mixes objects into the target object, recursively mixing existing child objects as well. In both cases, the key used to access the target object recursively is not checked, leading to exploiting this vulnerability. Note: This vulnerability derives from an incomplete fix of CVE-2020-7792.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | mout | all versions | 1.2.4npm install mout@1.2.4 |
Affected Products
moutmoutjsResearch 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 mout, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update mout to 1.2.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2022-21213 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.
Frequently Asked Questions
Is CVE-2022-21213 in your dependencies?
Find it across npm, including transitive dependencies.