How severe is CVE-2021-4303?

CVE-2021-4303 has a CVSS score of 6.1/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2021-4303?

CVE-2021-4303 affects the following packages: xataface/xataface (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2021-4303?

Update xataface/xataface to 3.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-4303 is resolved across your whole dependency graph.

How do I detect CVE-2021-4303 in my Packagist dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for xataface/xataface. 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.

How do I mitigate CVE-2021-4303 if there is no patch (or I can't update yet)?

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 does O3 Security protect against CVE-2021-4303?

O3 pinpoints whether CVE-2021-4303 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2021-4303 actively exploited in the wild?

No public exploit code has been indexed for CVE-2021-4303 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2021-4303?

CVE-2021-4303 has an EPSS (Exploit Prediction Scoring System) score of 0.5%, placing it in the 39th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2021-4303?

CVE-2021-4303 is classified as Cross-site Scripting (XSS) (CWE-79). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2021-4303 published, and has it been updated?

CVE-2021-4303 was published on January 5, 2023 and was last updated on April 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CVE-2021-4303: Xataface vulnerable to Cross-site Scripting (Med…

EPSS Exploitation Probability

via FIRST.org ↗

0.5%probability of exploitation in next 30 days

Lower Risk39th percentile+0.20%

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

1 pkg affected

🐘xataface/xataface

Real-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

A vulnerability, which was classified as problematic, has been found in shannah Xataface up to 2.x. Affected by this issue is the function testftp of the file install/install_form.js.php of the component Installer. The manipulation leads to cross site scripting. The attack may be launched remotely. The complexity of an attack is rather high. The exploitation is known to be difficult. Upgrading to version 3.0.0 is able to address this issue. The patch is identified as 94143a4299e386f33bf582139cd4702571d93bde. It is recommended to upgrade the affected component. VDB-217442 is the identifier assigned to this vulnerability. NOTE: Installer is disabled by default.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`xataface/xataface`	all versions	3.0.0

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for xataface/xataface. 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 xataface/xataface to 3.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-4303 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 CVE-2021-4303 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 CVE-2021-4303. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

A vulnerability, which was classified as problematic, has been found in shannah Xataface up to 2.x. Affected by this issue is the function testftp of the file install/install_form.js.php of the component Installer. The manipulation leads to cross site scripting. The attack may be launched remotely. The complexity of an attack is rather high. The exploitation is known to be difficult. Upgrading to version 3.0.0 is able to address this issue. The patch is identified as 94143a4299e386f33bf582139cd4702571d93bde. It is recommended to upgrade the affected component. VDB-217442 is the identifier assi

O3 Security · Impact-Aware SCA

Is CVE-2021-4303 in your dependencies?

O3 detects CVE-2021-4303 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works

CVE-2021-4303