CVE-2026-33228
9.8 · CRITICALOverview
CVE-2026-33228 is a critical-severity vulnerability affecting webreflection flatted. It was published on March 20, 2026 and has a CVSS 3.1 base score of 9.8 (CRITICAL).
This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
flatted is a circular JSON parser. Prior to version 3.4.2, the parse() function in flatted can use attacker-controlled string values from the parsed JSON as direct array index keys, without validating that they are numeric. Since the internal input buffer is a JavaScript Array, accessing it with the key "__proto__" returns Array.prototype via the inherited getter. This object is then treated as a legitimate parsed value and assigned as a property of the output object, effectively leaking a live reference to Array.prototype to the consumer. Any code that subsequently writes to that property will pollute the global prototype. This issue has been patched in version 3.4.2.
Remediation
Check the references section for vendor advisories and patches from webreflection. Update flatted to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| webreflection | flatted | >= 0, < 3.4.2 | Affected |
References
Frequently Asked Questions
What is CVE-2026-33228?
CVE-2026-33228 is a critical-severity vulnerability affecting webreflection flatted. It was published on March 20, 2026 and has a CVSS 3.1 base score of 9.8 (CRITICAL).
How severe is CVE-2026-33228?
This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2026-33228?
Check the references section for vendor advisories and patches from webreflection. Update flatted to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-33228?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-33228 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
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