CVE-2020-12827 is a high-severity (CVSS 7.2) Path Traversal vulnerability in mjml. 2 public exploit or proof-of-concept references are indexed, so weaponization risk is real. A fix is available for mjml — see the affected versions and patch details below.
MJML vulnerable to path traversal
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.
mjmlnpmDescription
MJML prior to 4.6.3 contains a path traversal vulnerability when processing the mj-include directive within an MJML document.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | mjml | all versions | 4.6.3npm install mjml@4.6.3 |
Affected Products
mjmlmjmlResearch 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 mjml, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update mjml to 4.6.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-12827 is resolved across your whole dependency graph.
Workarounds
Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.
Frequently Asked Questions
Is CVE-2020-12827 in your dependencies?
Find it across npm, including transitive dependencies.