What’s Vulnerable › Vulnerabilities

CVE-2026-59877: protobufjs: Denial of Service via infinite loop in .proto option parsing

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-08 · updated 2026-10-25
• Weakness: CWE-835

Description

protobufjs compiles protobuf definitions into JavaScript (JS) functions. Prior to 7.6.5 and 8.6.6, protobufjs parsed option names by advancing through schema tokens until reaching an = token without checking for end of input, so a crafted .proto schema that opens an option declaration and ends prematurely can cause parse, Root.load, or Root.loadSync to loop indefinitely. This issue is fixed in versions 7.6.5 and 8.6.6.

Affected products

• protobufjs: before 7.6.5; from 8.0.0 before 8.6.6 — fixed in 7.6.5, 8.6.6

How to fix

Upgrade to a fixed version: protobufjs 7.6.5, 8.6.6. Check the vendor advisory for mitigations.

References

• https://github.com/protobufjs/protobuf.js/commit/10fba6d54815ceecca8a06b9a6db490c8f5d2217
• https://github.com/protobufjs/protobuf.js/commit/fa5c73add738ceb471e74da8cc2f3727c3d0a69f
• https://github.com/protobufjs/protobuf.js/pull/2352
• https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v7.6.5
• https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v8.6.6
• https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-j3f2-48v5-ccww

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