CVE-2026-84375
js-yaml: maxTotalMergeKeys does not limit CPU use for empty merge sources
At a glance
- Source
- NVD
- EPSS
- EPSS 0.54 % · percentile 45 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- GitHub_M
- NVD status
- Deferred
Description
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.
Weaknesses (CWE)
References
- https://github.com/nodeca/js-yaml/security/advisories/GHSA-2883-xcg3-v3hh
- https://github.com/nodeca/js-yaml/pull/797
- https://github.com/nodeca/js-yaml/commit/3485bc06ff8a0251505f44a00414d90df2466639
- https://github.com/nodeca/js-yaml/commit/6a8e05f9a485188ed730ac81e81ae221352ef480
- https://github.com/nodeca/js-yaml/commit/d90b6612a5a84385bdcb556c44578eac76dc0f6b
- https://github.com/nodeca/js-yaml/releases/tag/3.15.2
- https://github.com/nodeca/js-yaml/releases/tag/4.3.2
- https://github.com/nodeca/js-yaml/releases/tag/5.4.1
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | HIGH 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | GitHub_M |
| CVSS 3.1 | HIGH 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | NVD · security-advisories@github.com (Secondary) |
Advisories
- GHSA-2883-xcg3-v3hh — js-yaml: maxTotalMergeKeys does not limit CPU use for empty merge sources
European references
- ENISA EUVD · EUVD-2026-69712
- GCVE · GCVE-0-2026-84375
CERT-FR advisories
- CERTFR-2026-AVI-1385 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr
- CERTFR-2026-AVI-1336 — Multiples vulnérabilités dans les produits IBM · cert.ssi.gouv.fr
- CERTFR-2026-AVI-1293 — Multiples vulnérabilités dans MongoDB · cert.ssi.gouv.fr
- CERTFR-2026-AVI-1256 — Multiples vulnérabilités dans les produits IBM · cert.ssi.gouv.fr
- CERTFR-2026-AVI-1233 — Multiples vulnérabilités dans les produits IBM · cert.ssi.gouv.fr
Affected products
| Product | Versions |
|---|---|
| nodeca · js-yaml | affected >= 3.0.0, < 3.15.2 ; affected >= 4.0.0, < 4.3.2 ; affected >= 5.0.0, < 5.4.1 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| CERT-FR (ANSSI) | Licence Ouverte / Etalab 2.0 |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |