GHSA-578p-fxmm-6229
HIGHPotentially untrusted input is rendered as HTML in final output
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.
Blast Radius
mjmlReal-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
All users of mjml-python who insert untrusted data into mjml templates unless that data is checked in a very strict manner. User input like <script> would be rendered as <script> in the final HTML output.
The attacker must be able to control some data which is later injected in an mjml template which is then send out as email to other users. The attacker could control contents of email messages sent through the platform.
Patches
The problem has been fixed in version 0.11.0 of this library. Versions before 0.10.0 are not affected by this security issue which was added as part of commit 84c495da20a91640a1ca551ace17df7f3be644aa.
Workarounds
- Ensure that potentially untrusted user input does not contain any sequences which could be rendered as HTML.
References
- Initial issue report by @sh-at-cs in #52
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | mjml | ≥ 0.10.0&&< 0.11.0 | 0.11.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mjml. 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 mjml to 0.11.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-578p-fxmm-6229 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 GHSA-578p-fxmm-6229 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 GHSA-578p-fxmm-6229. 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-578p-fxmm-6229 in your dependencies?
O3 detects GHSA-578p-fxmm-6229 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.