{"id":"UBUNTU-CVE-2026-84375","details":"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 \u003c\u003c. 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.","modified":"2026-10-17T12:56:15.919228010Z","published":"2026-09-01T22:17:00Z","upstream":["CVE-2026-84375"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-84375"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-84375"},{"type":"REPORT","url":"https://github.com/nodeca/js-yaml/security/advisories/GHSA-2883-xcg3-v3hh"},{"type":"REPORT","url":"https://github.com/nodeca/js-yaml/pull/797"}],"affected":[{"package":{"name":"node-js-yaml","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/node-js-yaml?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.9.1+dfsg-1","3.10.0+dfsg-1"],"ecosystem_specific":{"binaries":[{"binary_name":"node-js-yaml","binary_version":"3.10.0+dfsg-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-84375.json"}},{"package":{"name":"node-js-yaml","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/node-js-yaml?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.13.1+dfsg-2"],"ecosystem_specific":{"binaries":[{"binary_name":"node-js-yaml","binary_version":"3.13.1+dfsg-2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-84375.json"}},{"package":{"name":"node-js-yaml","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/node-js-yaml?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.14.1+dfsg+~3.12.6-2","4.1.0+dfsg+~4.0.5-4ubuntu1","4.1.0+dfsg+~4.0.5-5","4.1.0+dfsg+~4.0.5-6"],"ecosystem_specific":{"binaries":[{"binary_name":"node-js-yaml","binary_version":"4.1.0+dfsg+~4.0.5-6"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-84375.json"}},{"package":{"name":"node-js-yaml","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/node-js-yaml?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.1.0+dfsg+~4.0.5-7"],"ecosystem_specific":{"binaries":[{"binary_name":"node-js-yaml","binary_version":"4.1.0+dfsg+~4.0.5-7"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-84375.json"}},{"package":{"name":"node-js-yaml","ecosystem":"Ubuntu:26.10","purl":"pkg:deb/ubuntu/node-js-yaml?arch=source&distro=stonking"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.1.1+dfsg+~4.0.9-1","4.2.0+~4.0.9-1","4.2.0+~4.0.9-2"],"ecosystem_specific":{"binaries":[{"binary_name":"node-js-yaml","binary_version":"4.2.0+~4.0.9-2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-84375.json"}},{"package":{"name":"node-js-yaml","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/node-js-yaml?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.1.0+dfsg+~4.0.5-7","4.1.1+dfsg+~4.0.9-1"],"ecosystem_specific":{"binaries":[{"binary_name":"node-js-yaml","binary_version":"4.1.1+dfsg+~4.0.9-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-84375.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},{"type":"Ubuntu","score":"medium"}]}