High 7.5Published Sep 1, 2026

CVE-2026-84375js-yaml: maxTotalMergeKeys does not limit CPU use for empty merge sources

Updated under an hour ago (Oct 26, 2026, 10:10 PM ET)

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Every CVE for nodeca js-yaml

Exploited in the last 30 days

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.

CVSS: 7.5 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): CWE-400, CWE-407
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Deferred
Record last updated: Sep 28, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

nodeca js-yaml nodeca:js_yaml (from the name)	from 3.0.0, < 3.15.2; from 4.0.0, < 4.3.2; from 5.0.0, < 5.4.1	CNA record

References

References

https://github.com/nodeca/js-yaml/security/advisories/GHSA-2883-xcg3-v3hh	x-refsource-confirm
https://github.com/nodeca/js-yaml/pull/797	x-refsource-misc
https://github.com/nodeca/js-yaml/commit/3485bc06ff8a0251505f44a00414d90df2466639	x-refsource-misc
https://github.com/nodeca/js-yaml/commit/6a8e05f9a485188ed730ac81e81ae221352ef480	x-refsource-misc
https://github.com/nodeca/js-yaml/commit/d90b6612a5a84385bdcb556c44578eac76dc0f6b	x-refsource-misc
https://github.com/nodeca/js-yaml/releases/tag/3.15.2	x-refsource-misc
https://github.com/nodeca/js-yaml/releases/tag/4.3.2	x-refsource-misc
https://github.com/nodeca/js-yaml/releases/tag/5.4.1	x-refsource-misc

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.