{"cve":"CVE-2026-59876","nvd":{"published":"2026-07-08T16:16:34.233","modified":"2026-10-25T17:10:00.197","status":"Analyzed","description":"protobufjs compiles protobuf definitions into JavaScript (JS) functions. From 8.2.0 until 8.6.5, the protobufjs Text Format extension parsed string-keyed map entries using ordinary property assignment, allowing a map entry with key __proto__ to change the prototype of the returned map object instead of creating an own map entry in protobufjs/ext/textformat. This issue is fixed in version 8.6.5.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","score":4.8},"cwes":["CWE-1321"],"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"],"products":["protobufjs_project:protobufjs"],"source":"nvd","synced_at":"2026-10-25T17:50:06.907763985+00:00"},"epss":{"cve":"CVE-2026-59876","score":0.00349,"percentile":0.28288,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-jfj6-75fj-8934","url":"https://osv.dev/vulnerability/GHSA-jfj6-75fj-8934","summary":"protobufjs: Text Format string map parsing can mutate returned map object prototype","modified":"2026-09-10T03:50:12.269296263Z","packages":[{"ecosystem":"npm","name":"protobufjs","purl":"pkg:npm/protobufjs","ranges":[">=8.2.0 <8.6.5"],"fixed":["8.6.5"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}