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This issue is fixed in version 8.6.5.","state":0,"publishedAt":"2026-07-08T16:16:34.233+00:00","modifiedAt":"2026-10-25T17:10:00.197+00:00","affected":[],"metrics":[{"system":"CVSS 3.1 · security-advisories@github.com · Secondary","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","score":4.8,"severity":"MEDIUM"},{"system":"CVSS 3.1 · nvd@nist.gov · Primary","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","score":4.8,"severity":"MEDIUM"}],"references":["https://github.com/protobufjs/protobuf.js/commit/9f97fe413072d3beb52c74e62d88ea8adc9444d8","https://github.com/protobufjs/protobuf.js/pull/2335","https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v8.6.5","https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-jfj6-75fj-8934"],"sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-59876","license":"NIST NVD usage terms; underlying source attribution retained","enrichment":{"sourceStatus":"Analyzed","weaknesses":["CWE-1321"],"productCriteria":["cpe:2.3:a:protobufjs_project:protobufjs:*:*:*:*:*:node.js:*:*"],"sourceDates":{"published":"2026-07-08T16:16:34.233","lastModified":"2026-10-25T17:10:00.197"},"relatedAdvisories":[],"note":"NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON."},"key":"nvd:CVE-2026-59876","identifiers":["CVE-2026-59876"]},"retained":false,"historicalAffected":[]},{"revision":"e08ca674f6a34fafacdce259f3c4bcea","observedAt":"2026-10-24T13:17:17.793+00:00","statement":{"source":"osv","id":"GHSA-jfj6-75fj-8934","aliases":["CVE-2026-59876"],"title":"protobufjs: Text Format string map parsing can mutate returned map object prototype","description":"## Summary\n\nThe protobuf.js text format extension parsed string-keyed map entries using ordinary property assignment. A text-format map entry with key `__proto__` could therefore change the prototype of the returned map object instead of creating an own map entry.\n\nThis affected the optional Text Format extension. Other protobufjs input paths, including binary decode, `fromObject`, and ProtoJSON conversion, are not affected.\n\n## Impact\n\nAn attacker who can provide protobuf text-format input parsed by an application using `protobufjs/ext/textformat` may be able to create message objects whose string-keyed map fields have attacker-controlled prototypes.\n\nThis is per-object prototype mutation, not global `Object.prototype` pollution. Impact depends on downstream application logic treating inherited properties as meaningful, for example by using `in`, truthiness checks, or direct property access on parsed map objects instead of own-property checks.\n\nApplications that do not parse untrusted Text Format input, or that do not use inherited properties from parsed map objects in security-relevant logic, are not directly affected.\n\n## Preconditions\n\n* The application must parse attacker-controlled protobuf Text Format input with `protobufjs/ext/textformat`.\n* The target schema must contain a string-keyed map field.\n* The crafted input must provide a map entry with key `__proto__`.\n* Downstream application logic must treat inherited properties on the returned map object as meaningful for impact beyond malformed output.\n\n## Workarounds\n\nUpgrade to protobufjs 8.6.5 or newer.\n\nIf immediate upgrade is not possible, do not parse untrusted protobuf Text Format input with affected versions. Applications can also reject string map keys named `__proto__` before or during Text Format parsing, and should use own-property checks such as `Object.hasOwnProperty.call(map, key)` when consuming parsed map objects.","state":0,"publishedAt":"2026-07-20T22:04:07+00:00","modifiedAt":"2026-09-10T03:50:12.2692963+00:00","affected":[{"ecosystem":"npm","name":"protobufjs","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"8.2.0"},{"kind":"fixed","version":"8.6.5"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V3","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"MODERATE"}],"references":["https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-jfj6-75fj-8934","https://nvd.nist.gov/vuln/detail/CVE-2026-59876","https://github.com/protobufjs/protobuf.js/pull/2335","https://github.com/protobufjs/protobuf.js/commit/9f97fe413072d3beb52c74e62d88ea8adc9444d8","https://github.com/protobufjs/protobuf.js","https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v8.6.5"],"sourceUrl":"https://github.com/advisories/GHSA-jfj6-75fj-8934","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-jfj6-75fj-8934","identifiers":["GHSA-jfj6-75fj-8934","CVE-2026-59876"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. Missing entries do not establish absence of exploitation.","generation":"2026-11-07T20:52:46.7845564+00:00","complete":true,"records":1769,"lastAttemptAt":"2026-11-07T20:52:46.7845564+00:00","lastSuccessAt":"2026-11-07T20:52:46.9707302+00:00","error":null,"lastVerifiedAt":"2026-11-07T20:52:46.9707321+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"cve-program","scope":"Official CVE Program baseline and cumulative hourly delta; all vendors, published and rejected records","generation":"cve-bb5c9d5a08063ef076042e33dd72a7d0ffa4c4487efdcf3106e29ba55ec2ad57-1766179264875bb4621a23ce4c6bcebec63fb794a16e35c2f5592f4ee300ee2e","complete":true,"records":420944,"lastAttemptAt":"2026-11-07T20:52:46.1142943+00:00","lastSuccessAt":"2026-11-07T20:52:46.0341312+00:00","error":null,"lastVerifiedAt":"2026-11-07T20:52:46.1142943+00:00","snapshotPublishedAt":"2026-11-07T20:26:36+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"euvd","scope":"Rolling EUVD lookups of CVE aliases in current public OSV archives; 500 identifiers per refresh, rechecked after 48 hours. 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Not a global EPSS backfill.","generation":"2026-11-07T20:52:46.7845564+00:00","complete":true,"records":1096,"lastAttemptAt":"2026-11-07T20:52:46.7845564+00:00","lastSuccessAt":"2026-11-07T20:52:47.1482288+00:00","error":null,"lastVerifiedAt":"2026-11-07T20:52:47.1482303+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"nvd","scope":"Rolling NVD lookups of CVE aliases in current public OSV archives; 500 identifiers per refresh, rechecked after 48 hours. Not a global NVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. 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