GHSA-86pv-95mj-7w5f
HIGHStored XSS vulnerability on Bounce Management Callback
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
mautic/core🐘mautic/coreReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
Impact
Insufficient sanitization / filtering allows for arbitrary JavaScript Injection in Mautic using the bounce management callback function. The values submitted in the "error" and "error_related_to" parameters of the POST request of the bounce management callback will be permanently stored and executed once the details page of an affected lead is opened by a Mautic user.
An attacker with access to the bounce management callback function (identified with the Mailjet webhook, but it is assumed this will work uniformly across all kinds of webhooks) can inject arbitrary JavaScript Code into the "error" and "error_related_to" parameters of the POST request (POST /mailer/<product / webhook>/callback). It is noted that there is no authentication needed to access this function.
The JavaScript Code is stored permanently in the web application and executed every time an authenticated user views the details page of a single contact / lead in Mautic. This means, arbitrary code can be executed to, e.g., steal or tamper with information.
Patches
Upgrade to 3.3.4 or 4.0.0
Workarounds
No
References
https://github.com/mautic/mautic/releases/tag/3.3.4 https://github.com/mautic/mautic/releases/tag/4.0.0
For more information
If you have any questions or comments about this advisory:
- Email us at [email protected]
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | mautic/core | all versions | 3.3.4 |
| 🐘Packagist | mautic/core | ≥ 4.0.0-alpha1&&< 4.0.0 | 4.0.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mautic/core. 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 mautic/core to 3.3.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-86pv-95mj-7w5f 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-86pv-95mj-7w5f 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-86pv-95mj-7w5f. 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-86pv-95mj-7w5f in your dependencies?
O3 detects GHSA-86pv-95mj-7w5f across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.