GitHub Advisoryadvisory · npm

GHSA-j3f2-48v5-ccww protobufjs: Denial of Service via infinite loop in .proto option parsing

MEDIUM Published 2026-07-20 Modified 2026-07-20 Official page ↗
Aliases
CVE-2026-59877
Ecosystem
npm
Packages
protobufjs
Severity
Moderate
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Weaknesses
CWE-835
Reviewed
2026-07-20

Affected packages

• npm protobufjs: >= 7.5.0, < 7.6.5 → fixed in 7.6.5 • npm protobufjs: >= 8.0.0, < 8.6.6 → fixed in 8.6.6

Description

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 `.proto` schema text influenced by an attacker. • The schema must be parsed through APIs such as `parse`, `Root.load`, or `Root.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.

Related

Alias · CVE (1)

  • CVE-2026-59877 protobufjs compiles protobuf definitions into JavaScript (JS) functions. vulnerability

Weakness · CWE (1)

  • CWE-835 Loop with Unreachable Exit Condition weakness

References