High

gettext-converter: Prototype pollution in js2i18next() via crafted translation keys

Type: advisorySources: OSV

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.

Products: Not specified
Affected versions: Not specified
Fixed versions: Not specified
CVEs: CVE-2026-55451
Confirmed fixed CVEs: Not specified
Updated in this feed: 7 Nov 2026, 12:56 UTC · Revision 1

Source evidence

gettext-converter: Prototype pollution in js2i18next() via crafted translation keys

core-osv · Original source

Published 14 Sept 2026, 16:49 UTC

osv:CVE-2026-55451

Complete source record

{
  "id": "a8a0402e3a363372b63b0a7c93e395f165381d9410b4f362f2f5af05e1ab76bc",
  "url": "https://osv.dev/vulnerability/CVE-2026-55451",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "gettext-converter: Prototype pollution in js2i18next() via crafted translation keys",
    "summary": "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.",
    "evidence": "osv:CVE-2026-55451",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-55451",
      "aliases": [
        "CVE-2026-55451",
        "GHSA-f4jp-rw7w-ccwg"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "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"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/locize/gettext-converter",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "4b02e8c5c2a873b638a4d90bd8459213ba323724"
                },
                {
                  "fixed": "df90c3b93e51faef68891d97b626544f619c5b31"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "1.3.3"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "df90c3b93e51faef68891d97b626544f619c5b31"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "4b02e8c5c2a873b638a4d90bd8459213ba323724"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v1.3.3"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v1.3.2",
            "v1.3.1",
            "v1.3.0",
            "v1.2.4",
            "v1.2.3",
            "v1.2.2",
            "v1.2.1",
            "v1.2.0",
            "v1.1.3",
            "v1.1.2",
            "v1.1.1",
            "v1.1.0",
            "v1.0.8",
            "v1.0.7",
            "v1.0.6",
            "v1.0.5",
            "v1.0.4",
            "v1.0.3",
            "v1.0.2",
            "v1.0.1",
            "v1.0.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-55451.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:50.759822317Z",
      "provider": "osv",
      "references": [
        "https://github.com/locize/gettext-converter/releases/tag/v1.3.3",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55451.json",
        "https://github.com/locize/gettext-converter/security/advisories/GHSA-f4jp-rw7w-ccwg",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-55451",
        "https://github.com/locize/gettext-converter/issues/15",
        "https://github.com/locize/gettext-converter/commit/df90c3b93e51faef68891d97b626544f619c5b31"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-1321"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55451.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-55451",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 519358,
  "published_at": "2026-09-14T16:49:36.238+00:00"
}