{"id":"CVE-2026-59876","title":"protobufjs compiles protobuf definitions into JavaScript (JS) functions","summary":"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 __pro…","severity":"medium","cvss":4.8,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","cwe":["CWE-1321"],"vendor":"protobufjs_project","product":"protobufjs","affected":["protobufjs >= 8.2.0, < 8.6.5"],"patched":["protobufjs 8.6.5"],"published":"2026-07-08","updated":"2026-07-13","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-59876","references":[{"url":"https://github.com/protobufjs/protobuf.js/commit/9f97fe413072d3beb52c74e62d88ea8adc9444d8","label":"security-advisories@github.com"},{"url":"https://github.com/protobufjs/protobuf.js/pull/2335","label":"security-advisories@github.com"},{"url":"https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v8.6.5","label":"security-advisories@github.com"},{"url":"https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-jfj6-75fj-8934","label":"security-advisories@github.com"}],"tags":["nvd"],"epss":0.00349,"epssPercentile":0.28517,"ingestedAt":"2026-07-13T15:27:34.188Z","slug":"CVE-2026-59876","body":"## Overview\n\nprotobufjs 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.\n\n## Affected\n\n- `protobufjs >= 8.2.0, < 8.6.5`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `protobufjs 8.6.5`","depth":"sunlit","depthScore":26,"depthScoreParts":{"impact":26.4,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}