{"id":"CVE-2026-55451","aliases":["EUVD-2026-77634","GHSA-f4jp-rw7w-ccwg"],"status":"published","title":"gettext-converter: Prototype pollution in js2i18next() via crafted translation keys","description":"gettext-converter provides gettext resource conversion utilities for JavaScript. Prior to 1.3.3, js2i18next() in lib/js2i18next.js splits nested translation keys using options.keyseparator, whose default value consists of two number signs, and uses each segment as a dynamic object key without rejecting __proto__, constructor, or prototype. When an application converts untrusted PO or i18next translation data, a __proto__ segment resolves Object.prototype as the nested write target and Object.assign writes attacker-controlled translated properties onto the process-wide prototype. The resulting prototype pollution can cause denial of service and may enable application-dependent follow-on attacks. This issue is fixed in version 1.3.3.","severity":{"version":"4.0","score":8.3,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00566,"percentile":0.47412,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-1321"],"published":"2026-08-20T20:11:13Z","modified":"2026-10-28T02:30:50Z","fixes":[{"ecosystem":"npm","package":"gettext-converter","fixed_in":["1.3.3"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"npm","package":"gettext-converter","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.3.3"}]}]},{"source":"osv","ecosystem":"npm","package":"gettext-converter","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"1.3.3"}]}]}],"products":[{"vendor":"locize","product":"gettext-converter"}],"references":[{"url":"https://github.com/locize/gettext-converter/security/advisories/GHSA-f4jp-rw7w-ccwg","tags":["x_refsource_CONFIRM","advisory","web"]},{"url":"https://github.com/locize/gettext-converter/issues/15","tags":["x_refsource_MISC","exploit","report","web"]},{"url":"https://github.com/locize/gettext-converter/commit/df90c3b93e51faef68891d97b626544f619c5b31","tags":["x_refsource_MISC","fix","web"]},{"url":"https://github.com/locize/gettext-converter/releases/tag/v1.3.3","tags":["x_refsource_MISC","web"]},{"url":"https://github.com/advisories/GHSA-f4jp-rw7w-ccwg"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55451.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-55451","tags":["advisory"]},{"url":"https://github.com/locize/gettext-converter","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-55451","title":"gettext-converter: Prototype pollution in js2i18next() via crafted translation keys","description":"gettext-converter provides gettext resource conversion utilities for JavaScript. Prior to 1.3.3, js2i18next() in lib/js2i18next.js splits nested translation keys using options.keyseparator, whose default value consists of two number signs, and uses each segment as a dynamic object key without rejecting __proto__, constructor, or prototype. When an application converts untrusted PO or i18next translation data, a __proto__ segment resolves Object.prototype as the nested write target and Object.assign writes attacker-controlled translated properties onto the process-wide prototype. The resulting prototype pollution can cause denial of service and may enable application-dependent follow-on attacks. This issue is fixed in version 1.3.3.","status":"published","published":"2026-09-14T16:49:36.238Z","modified":"2026-09-14T18:53:39.96Z","cvss":[{"version":"4.0","score":8.3,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N","level":"high","assessor":"cna"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T14:20:12.260247Z"}],"euvd":[{"id":"EUVD-2026-77634","description":"gettext-converter provides gettext resource conversion utilities for JavaScript. Prior to 1.3.3, js2i18next() in lib/js2i18next.js splits nested translation keys using options.keyseparator, whose default value consists of two number signs, and uses each segment as a dynamic object key without rejecting __proto__, constructor, or prototype. When an application converts untrusted PO or i18next translation data, a __proto__ segment resolves Object.prototype as the nested write target and Object.assign writes attacker-controlled translated properties onto the process-wide prototype. The resulting prototype pollution can cause denial of service and may enable application-dependent follow-on attacks. This issue is fixed in version 1.3.3.","status":"published","published":"2026-09-14T16:49:36Z","modified":"2026-09-14T18:53:39Z","cvss":[{"version":"4.0","score":8.3,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N","level":"high"}],"updated_at":"2026-11-02T17:28:19.730872Z"}],"ghsa":[{"id":"GHSA-f4jp-rw7w-ccwg","title":"gettext-converter: Prototype pollution in js2i18next() via crafted translation keys","description":"### Impact\n\n`js2i18next()` is vulnerable to prototype pollution. When converting translations, it splits nested keys on the key separator (default `##`) and uses each segment as a dynamic object key while building the output object. A key whose segment is `__proto__` (e.g. `__proto__##gcPolluted`) causes the converter to resolve `Object.prototype` as the nested write target and assign the translated value onto it, polluting `Object.prototype` for the whole runtime.\n\nAny application that converts translation data (PO / i18next JS objects) originating from an untrusted or user-controlled source is affected. Prototype pollution can lead to denial of service and, depending on the surrounding application, may enable further attacks.\n\n### Patches\n\nFixed in `gettext-converter@1.3.3`. Key segments equal to `__proto__`, `constructor`, or `prototype` are now rejected before being used as dynamic object keys.\n\n### Workarounds\n\nUpgrade to `1.3.3`. If upgrading is not immediately possible, sanitize/validate translation keys before passing them to `js2i18next()` and reject any key whose `##`-separated segments include `__proto__`, `constructor`, or `prototype`.","status":"published","published":"2026-08-20T20:11:13Z","modified":"2026-08-20T20:11:15Z","cvss":[{"version":"4.0","score":6.9,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","level":"medium"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T14:41:04.755504Z"}],"nvd":[{"id":"CVE-2026-55451","description":"gettext-converter provides gettext resource conversion utilities for JavaScript. Prior to 1.3.3, js2i18next() in lib/js2i18next.js splits nested translation keys using options.keyseparator, whose default value consists of two number signs, and uses each segment as a dynamic object key without rejecting __proto__, constructor, or prototype. When an application converts untrusted PO or i18next translation data, a __proto__ segment resolves Object.prototype as the nested write target and Object.assign writes attacker-controlled translated properties onto the process-wide prototype. The resulting prototype pollution can cause denial of service and may enable application-dependent follow-on attacks. This issue is fixed in version 1.3.3.","status":"published","published":"2026-09-14T17:17:48.383Z","modified":"2026-09-30T19:57:08.043Z","cvss":[{"version":"4.0","score":8.3,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high","assessor":"secondary"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T14:12:46.980627Z"}],"osv":[{"id":"CVE-2026-55451","title":"gettext-converter: Prototype pollution in js2i18next() via crafted translation keys","description":"gettext-converter provides gettext resource conversion utilities for JavaScript. Prior to 1.3.3, js2i18next() in lib/js2i18next.js splits nested translation keys using options.keyseparator, whose default value consists of two number signs, and uses each segment as a dynamic object key without rejecting __proto__, constructor, or prototype. When an application converts untrusted PO or i18next translation data, a __proto__ segment resolves Object.prototype as the nested write target and Object.assign writes attacker-controlled translated properties onto the process-wide prototype. The resulting prototype pollution can cause denial of service and may enable application-dependent follow-on attacks. This issue is fixed in version 1.3.3.","status":"published","published":"2026-09-14T16:49:36.238Z","modified":"2026-10-28T02:30:50.759822317Z","cvss":[{"version":"4.0","score":8.3,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T15:45:11.22012Z"},{"id":"GHSA-f4jp-rw7w-ccwg","title":"gettext-converter: Prototype pollution in js2i18next() via crafted translation keys","description":"### Impact\n\n`js2i18next()` is vulnerable to prototype pollution. When converting translations, it splits nested keys on the key separator (default `##`) and uses each segment as a dynamic object key while building the output object. A key whose segment is `__proto__` (e.g. `__proto__##gcPolluted`) causes the converter to resolve `Object.prototype` as the nested write target and assign the translated value onto it, polluting `Object.prototype` for the whole runtime.\n\nAny application that converts translation data (PO / i18next JS objects) originating from an untrusted or user-controlled source is affected. Prototype pollution can lead to denial of service and, depending on the surrounding application, may enable further attacks.\n\n### Patches\n\nFixed in `gettext-converter@1.3.3`. Key segments equal to `__proto__`, `constructor`, or `prototype` are now rejected before being used as dynamic object keys.\n\n### Workarounds\n\nUpgrade to `1.3.3`. If upgrading is not immediately possible, sanitize/validate translation keys before passing them to `js2i18next()` and reject any key whose `##`-separated segments include `__proto__`, `constructor`, or `prototype`.","status":"published","published":"2026-08-20T20:11:13Z","modified":"2026-08-20T20:26:04.313226Z","cvss":[{"version":"4.0","score":6.9,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","level":"medium"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T15:46:46.006631Z"}]}}