Review reviewHigh

CVE-2026-59877

protobufjs protobuf.js, protobufjs

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.

CVSS: 7.5
EPSS: 0.37%
CISA KEV: Not listed
Published: 2026.07.09

PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability0.37%

Technical severityCVSS 7.5

Vulnerability overview

Affected product and versions

Product: protobufjs protobuf.js, protobufjs
Affected versions: >= 7.5.0, < 7.6.5, >= 8.0.0, < 8.6.6, >= 8.0.0 < 8.6.6
Fixed versions: 7.6.5, 8.6.6

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide

1
Identify
Confirm that protobufjs protobuf.js, protobufjs and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE: CWE-835