{"cve":"CVE-2026-53550","nvd":{"published":"2026-06-22T16:16:38.447","modified":"2026-10-25T23:10:00.167","status":"Analyzed","description":"js-yaml is a JavaScript YAML parser and dumper. Prior to 4.2.0 and 3.15.0, a crafted YAML document can trigger algorithmic CPU exhaustion in js-yaml merge-key processing (<<) by repeating the same alias many times in a merge sequence. This causes quadratic parse-time behavior relative to input size and can block a Node.js worker/event loop for seconds with a relatively small payload (tens of KB), resulting in denial of service. The issue is in merge handling inside lib/loader.js. This vulnerability is fixed in 4.2.0 and 3.15.0.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","score":5.3},"cwes":["CWE-407"],"references":["https://github.com/nodeca/js-yaml/security/advisories/GHSA-h67p-54hq-rp68"],"products":["nodeca:js-yaml"],"source":"nvd","synced_at":"2026-10-25T23:44:33.281319194+00:00"},"epss":{"cve":"CVE-2026-53550","score":0.00415,"percentile":0.35557,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-h67p-54hq-rp68","url":"https://osv.dev/vulnerability/GHSA-h67p-54hq-rp68","summary":"JS-YAML: Quadratic-complexity DoS in merge key handling via repeated aliases","modified":"2026-09-10T03:50:49.729923880Z","packages":[{"ecosystem":"npm","name":"js-yaml","purl":"pkg:npm/js-yaml","ranges":[">=4.0.0 <4.2.0"],"fixed":["4.2.0"]},{"ecosystem":"npm","name":"js-yaml","purl":"pkg:npm/js-yaml","ranges":["<3.15.0"],"fixed":["3.15.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}