{"id":"CVE-2026-84375","sourceIdentifier":"security-advisories@github.com","published":"2026-09-01T22:17:19.440","lastModified":"2026-09-28T22:17:33.377","vulnStatus":"Deferred","cveTags":[],"descriptions":[{"lang":"en","value":"js-yaml is a JavaScript YAML parser and dumper. From 3.0.0 until 3.15.2, 4.3.2, and 5.4.1, maxTotalMergeKeys in lib/js-yaml/loader.js and lib/loader.js does not count empty mapping sources while processing the merge key <<. An attacker can alias a large sequence of empty mappings into many merge targets, causing O(N * K) processing while totalMergeKeys remains unchanged and the configured resource limit is never reached. A relatively small YAML document can therefore cause prolonged CPU consumption in applications that parse untrusted YAML, and merge processing is enabled by default on these release lines. In v3 & v4, merge is enabled by default so the severity score is higher. This issue is fixed in versions 3.15.2, 4.3.2, and 5.4.1."}],"affected":[{"source":"security-advisories@github.com","affectedData":[{"vendor":"nodeca","product":"js-yaml","versions":[{"version":">= 3.0.0, < 3.15.2","status":"affected"},{"version":">= 4.0.0, < 4.3.2","status":"affected"},{"version":">= 5.0.0, < 5.4.1","status":"affected"}]}]}],"metrics":{"cvssMetricV31":[{"source":"security-advisories@github.com","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","baseScore":7.5,"baseSeverity":"HIGH","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"},"exploitabilityScore":3.9,"impactScore":3.6}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-09-02T13:43:50.850378Z","id":"CVE-2026-84375","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"weaknesses":[{"source":"security-advisories@github.com","type":"Secondary","description":[{"lang":"en","value":"CWE-400"},{"lang":"en","value":"CWE-407"}]}],"references":[{"url":"https://github.com/nodeca/js-yaml/commit/3485bc06ff8a0251505f44a00414d90df2466639","source":"security-advisories@github.com"},{"url":"https://github.com/nodeca/js-yaml/commit/6a8e05f9a485188ed730ac81e81ae221352ef480","source":"security-advisories@github.com"},{"url":"https://github.com/nodeca/js-yaml/commit/d90b6612a5a84385bdcb556c44578eac76dc0f6b","source":"security-advisories@github.com"},{"url":"https://github.com/nodeca/js-yaml/pull/797","source":"security-advisories@github.com"},{"url":"https://github.com/nodeca/js-yaml/releases/tag/3.15.2","source":"security-advisories@github.com"},{"url":"https://github.com/nodeca/js-yaml/releases/tag/4.3.2","source":"security-advisories@github.com"},{"url":"https://github.com/nodeca/js-yaml/releases/tag/5.4.1","source":"security-advisories@github.com"},{"url":"https://github.com/nodeca/js-yaml/security/advisories/GHSA-2883-xcg3-v3hh","source":"security-advisories@github.com"}]}