{"id":"CVE-2026-59876","sourceIdentifier":"security-advisories@github.com","published":"2026-07-08T16:16:34.233","lastModified":"2026-07-13T15:02:37.000","vulnStatus":"Analyzed","cveTags":[],"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."}],"affected":[{"source":"security-advisories@github.com","affectedData":[{"vendor":"protobufjs","product":"protobuf.js","versions":[{"version":">= 8.2.0, < 8.6.5","status":"affected"}]}]}],"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},{"source":"nvd@nist.gov","type":"Primary","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}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-07-09T14:41:36.435616Z","id":"CVE-2026-59876","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"weaknesses":[{"source":"security-advisories@github.com","type":"Secondary","description":[{"lang":"en","value":"CWE-1321"}]}],"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:protobufjs_project:protobufjs:*:*:*:*:*:node.js:*:*","versionStartIncluding":"8.2.0","versionEndExcluding":"8.6.5","matchCriteriaId":"8A2830C5-3D82-48A6-A85C-C6CD0D271B32"}]}]}],"references":[{"url":"https://github.com/protobufjs/protobuf.js/commit/9f97fe413072d3beb52c74e62d88ea8adc9444d8","source":"security-advisories@github.com","tags":["Patch"]},{"url":"https://github.com/protobufjs/protobuf.js/pull/2335","source":"security-advisories@github.com","tags":["Issue Tracking","Patch"]},{"url":"https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v8.6.5","source":"security-advisories@github.com","tags":["Product","Release Notes"]},{"url":"https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-jfj6-75fj-8934","source":"security-advisories@github.com","tags":["Mitigation","Vendor Advisory"]}]}