CVE-2021-3841 is a medium-severity (CVSS 5.4) Cross-site Scripting (XSS) vulnerability in sylius/sylius. A fix is available for sylius/sylius — see the affected versions and patch details below.
Cross site scripting in sylius/sylius
Exploitation Status
No confirmed exploitation observed yet
- 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 CVE-2021-3841.
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
sylius/sylius🐘sylius/sylius🐘sylius/syliusReal-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
sylius/sylius versions prior to 1.9.10, 1.10.11, and 1.11.2 are vulnerable to stored cross-site scripting (XSS) through SVG files. This vulnerability allows attackers to inject malicious scripts that can be executed in the context of the user's browser.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | sylius/sylius | all versions | 1.9.10composer require sylius/sylius:^1.9.10 |
| 🐘Packagist | sylius/sylius | ≥ 1.10.0&&< 1.10.11 | 1.10.11composer require sylius/sylius:^1.10.11 |
| 🐘Packagist | sylius/sylius | ≥ 1.11.0&&< 1.11.2 | 1.11.2composer require sylius/sylius:^1.11.2 |
Affected Products
syliussyliusDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for sylius/sylius, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update sylius/sylius to 1.9.10 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-3841 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.
Frequently Asked Questions
Is CVE-2021-3841 in your dependencies?
Find it across Packagist, including transitive dependencies.