{"api_version":"1","generated_at":"2026-07-08T18:27:46+00:00","cve":"CVE-2026-59876","urls":{"html":"https://cve.report/CVE-2026-59876","api":"https://cve.report/api/cve/CVE-2026-59876.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-59876","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-59876"},"summary":{"title":"protobufjs: Text Format string map parsing can mutate returned map object prototype","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.","state":"PUBLISHED","assigner":"GitHub_M","published_at":"2026-07-08 16:16:34","updated_at":"2026-07-08 16:16:34"},"problem_types":["CWE-1321","CWE-1321 CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')"],"metrics":[{"version":"3.1","source":"security-advisories@github.com","type":"Secondary","score":"4.8","severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","baseScore":4.8,"baseSeverity":"MEDIUM","attackVector":"NETWORK","attackComplexity":"HIGH","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"LOW","integrityImpact":"LOW","availabilityImpact":"NONE"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"4.8","severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","data":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":4.8,"baseSeverity":"MEDIUM","confidentialityImpact":"LOW","integrityImpact":"LOW","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","version":"3.1"}}],"references":[{"url":"https://github.com/protobufjs/protobuf.js/pull/2335","name":"https://github.com/protobufjs/protobuf.js/pull/2335","refsource":"security-advisories@github.com","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v8.6.5","name":"https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v8.6.5","refsource":"security-advisories@github.com","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-jfj6-75fj-8934","name":"https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-jfj6-75fj-8934","refsource":"security-advisories@github.com","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://github.com/protobufjs/protobuf.js/commit/9f97fe413072d3beb52c74e62d88ea8adc9444d8","name":"https://github.com/protobufjs/protobuf.js/commit/9f97fe413072d3beb52c74e62d88ea8adc9444d8","refsource":"security-advisories@github.com","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-59876","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-59876","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"protobufjs","product":"protobuf.js","version":"affected >= 8.2.0, < 8.6.5","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"product":"protobuf.js","vendor":"protobufjs","versions":[{"status":"affected","version":">= 8.2.0, < 8.6.5"}]}],"descriptions":[{"lang":"en","value":"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."}],"metrics":[{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":4.8,"baseSeverity":"MEDIUM","confidentialityImpact":"LOW","integrityImpact":"LOW","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-1321","description":"CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-07-08T15:31:11.421Z","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","shortName":"GitHub_M"},"references":[{"name":"https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-jfj6-75fj-8934","tags":["x_refsource_CONFIRM"],"url":"https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-jfj6-75fj-8934"},{"name":"https://github.com/protobufjs/protobuf.js/pull/2335","tags":["x_refsource_MISC"],"url":"https://github.com/protobufjs/protobuf.js/pull/2335"},{"name":"https://github.com/protobufjs/protobuf.js/commit/9f97fe413072d3beb52c74e62d88ea8adc9444d8","tags":["x_refsource_MISC"],"url":"https://github.com/protobufjs/protobuf.js/commit/9f97fe413072d3beb52c74e62d88ea8adc9444d8"},{"name":"https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v8.6.5","tags":["x_refsource_MISC"],"url":"https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v8.6.5"}],"source":{"advisory":"GHSA-jfj6-75fj-8934","discovery":"UNKNOWN"},"title":"protobufjs: Text Format string map parsing can mutate returned map object prototype"}},"cveMetadata":{"assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","assignerShortName":"GitHub_M","cveId":"CVE-2026-59876","datePublished":"2026-07-08T15:31:11.421Z","dateReserved":"2026-07-07T15:41:53.607Z","dateUpdated":"2026-07-08T15:31:11.421Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-07-08 16:16:34","lastModifiedDate":"2026-07-08 16:16:34","problem_types":["CWE-1321","CWE-1321 CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')"],"metrics":{"cvssMetricV31":[{"source":"security-advisories@github.com","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","baseScore":4.8,"baseSeverity":"MEDIUM","attackVector":"NETWORK","attackComplexity":"HIGH","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"LOW","integrityImpact":"LOW","availabilityImpact":"NONE"},"exploitabilityScore":2.2,"impactScore":2.5}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"59876","Ordinal":"1","Title":"protobufjs: Text Format string map parsing can mutate returned m","CVE":"CVE-2026-59876","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"59876","Ordinal":"1","NoteData":"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.","Type":"Description","Title":"protobufjs: Text Format string map parsing can mutate returned m"}]}}}