protobufjs: Denial of Service via infinite loop in .proto option parsing
Summary
protobufjs 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.
This affects the reflection parsing path (parse, Root.load, Root.loadSync).
Impact
An 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.
Applications that only encode or decode protobuf binary data with trusted schemas are not directly affected.
Preconditions
- The application must parse
.protoschema text influenced by an attacker. - The schema must be parsed through APIs such as
parse,Root.load, orRoot.loadSync. - The crafted input must begin an option declaration that ends before its
=assignment.
Workarounds
Do 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.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | protobufjs | >= 7.5.0, < 7.6.5, >= 8.0.0, < 8.6.6 | 7.6.5, 8.6.6 |
References
- https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-j3f2-48v5-ccww
- https://nvd.nist.gov/vuln/detail/CVE-2026-59877
- https://github.com/protobufjs/protobuf.js/pull/2352
- https://github.com/protobufjs/protobuf.js/commit/10fba6d54815ceecca8a06b9a6db490c8f5d2217
- https://github.com/protobufjs/protobuf.js/commit/fa5c73add738ceb471e74da8cc2f3727c3d0a69f
- https://github.com/protobufjs/protobuf.js
- https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v7.6.5
- https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v8.6.6
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L- Weakness (CWE)
CWE-835- Platform
- npm
- Package
protobufjs- Disclosed
- 20.07.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-j3f2-48v5-ccww - CC BY 4.0
Vulnerability history: protobufjs
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 17
- First → latest
- 10.2018 07.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 2
- High 6
- Medium 9
Disclosures per year
- 2018: 1
- 2019: 0
- 2020: 0
- 2021: 0
- 2022: 1
- 2023: 1
- 2024: 0
- 2025: 0
- 2026: 14
-
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