{"id":"CVE-2026-59877","aliases":["GHSA-j3f2-48v5-ccww"],"url":"https://o3.security/vulnerability/CVE-2026-59877","summary":"protobufjs: Denial of Service via infinite loop in .proto option parsing","details":"## Summary\n\nprotobufjs parsed option names by advancing through schema tokens until it reached an `=` token, without checking for end of input. A crafted `.proto` schema that opens an option declaration but ends prematurely could cause the option parser to loop without ever terminating.\n\nThis affects the reflection parsing path (`parse`, `Root.load`, `Root.loadSync`).\n\n## Impact\n\nAn attacker who can provide or influence `.proto` schema text parsed by an application may be able to cause the parsing call to never return. Because Node.js is single-threaded, the blocked event loop prevents all other work in the process, resulting in a denial of service that persists until the process is externally terminated.\n\nApplications that only encode or decode protobuf binary data with trusted schemas are not directly affected.\n\n## Preconditions\n\n- The application must parse `.proto` schema text influenced by an attacker.\n- The schema must be parsed through APIs such as `parse`, `Root.load`, or `Root.loadSync`.\n- The crafted input must begin an option declaration that ends before its `=` assignment.\n\n## Workarounds\n\nDo not parse `.proto` schemas from untrusted sources with affected versions. If untrusted schema text must be accepted, isolate parsing in a process or worker that can be safely terminated and bound it with a timeout, so a non-returning parse call cannot deny service to the rest of the application.","published":"2026-07-08T15:28:07.696Z","modified":"2026-08-12T03:51:44.412969728Z","cvss":{"score":5.3,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"},"epss":{"score":0.00365,"percentile":0.3016,"asOf":"2026-09-16"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"protobufjs","fixedVersion":"7.6.5"},{"ecosystem":"npm","name":"protobufjs","fixedVersion":"8.6.6"}],"fix":{"url":"https://github.com/protobufjs/protobuf.js/commit/10fba6d54815ceecca8a06b9a6db490c8f5d2217","label":"protobufjs/protobuf.js@10fba6d"},"references":[{"type":"WEB","url":"https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v7.6.5"},{"type":"WEB","url":"https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v8.6.6"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59877.json"},{"type":"ADVISORY","url":"https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-j3f2-48v5-ccww"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-59877"},{"type":"FIX","url":"https://github.com/protobufjs/protobuf.js/commit/10fba6d54815ceecca8a06b9a6db490c8f5d2217"},{"type":"FIX","url":"https://github.com/protobufjs/protobuf.js/commit/fa5c73add738ceb471e74da8cc2f3727c3d0a69f"},{"type":"FIX","url":"https://github.com/protobufjs/protobuf.js/pull/2352"},{"type":"PACKAGE","url":"https://github.com/protobufjs/protobuf.js"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:44.412969728Z"}}