High severity · published Jul 8, 2026
CVE-2026-59877
protobufjs: Denial of Service via infinite loop in .proto option parsing
7.5
CVSS
0.4%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 30% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
PR
protobuf.js · protobufjs
>= 7.5.0, < 7.6.5; >= 8.0.0, < 8.6.6 · source: vendor
PR
Protobufjs · Protobufjs Project
before 7.6.5; 8.0.0 before 8.6.6 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-59877
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-59877
Patch
https://github.com/protobufjs/protobuf.js/commit/10fba6d54815ceecca8a06b9a6db490c8f5d2217
Patch
https://github.com/protobufjs/protobuf.js/commit/fa5c73add738ceb471e74da8cc2f3727c3d0a69f
Issue Tracking
https://github.com/protobufjs/protobuf.js/pull/2352
Product
https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v7.6.5
Product
https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v8.6.6
Mitigation
https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-j3f2-48v5-ccww
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