medium

CVE-2026-59877

npm · protobufjs

Summary

protobufjs: Denial of Service via infinite loop in .proto option parsing

Severity
medium
CVSS
5.3
EPSS
0.4% (p30)
CWE
CWE-835
Also known as
GHSA-j3f2-48v5-ccww
Published
2026-07-20
Updated
2026-07-20

Advisory details

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

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.

References

Related advisories

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Sources: CISA KEV (public domain), OSV.dev & GitHub Advisory Database (CC-BY-4.0), FIRST EPSS, NVD/CWE (public domain). Served live from the Stateward advisory database.