CVE-2026-59877
protobufjs: Denial of Service via infinite loop in .proto option parsing
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.
INFO
Published Date :
July 8, 2026, 4:16 p.m.
Last Modified :
July 10, 2026, 6:53 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Update protobufjs to version 7.6.5 or later.
- Update protobufjs to version 8.6.6 or later.
Public PoC/Exploit Available at Github
CVE-2026-59877 has a 2 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-59877.
| URL | Resource |
|---|---|
| https://github.com/protobufjs/protobuf.js/commit/10fba6d54815ceecca8a06b9a6db490c8f5d2217 | Patch |
| https://github.com/protobufjs/protobuf.js/commit/fa5c73add738ceb471e74da8cc2f3727c3d0a69f | Patch |
| https://github.com/protobufjs/protobuf.js/pull/2352 | Issue Tracking Patch |
| https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v7.6.5 | Product Release Notes |
| https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v8.6.6 | Product Release Notes |
| https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-j3f2-48v5-ccww | Mitigation Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-59877 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-59877
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
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Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-59877 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-59877 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Jul. 10, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added CPE Configuration OR *cpe:2.3:a:protobufjs_project:protobufjs:*:*:*:*:*:node.js:*:* versions up to (excluding) 7.6.5 *cpe:2.3:a:protobufjs_project:protobufjs:*:*:*:*:*:node.js:*:* versions from (including) 8.0.0 up to (excluding) 8.6.6 Added Reference Type GitHub, Inc.: https://github.com/protobufjs/protobuf.js/commit/10fba6d54815ceecca8a06b9a6db490c8f5d2217 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/protobufjs/protobuf.js/commit/fa5c73add738ceb471e74da8cc2f3727c3d0a69f Types: Patch Added Reference Type GitHub, Inc.: https://github.com/protobufjs/protobuf.js/pull/2352 Types: Issue Tracking, Patch Added Reference Type GitHub, Inc.: https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v7.6.5 Types: Product, Release Notes Added Reference Type GitHub, Inc.: https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v8.6.6 Types: Product, Release Notes Added Reference Type GitHub, Inc.: https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-j3f2-48v5-ccww Types: Mitigation, Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 08, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-59877', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-07-08T15:48:58.903197Z'} -
New CVE Received by [email protected]
Jul. 08, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'protobufjs', 'product': 'protobuf.js', 'versions': [{'status': 'affected', 'version': '>= 7.5.0, < 7.6.5'}, {'status': 'affected', 'version': '>= 8.0.0, < 8.6.6'}]}] Added 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. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Added CWE CWE-835 Added Reference https://github.com/protobufjs/protobuf.js/commit/10fba6d54815ceecca8a06b9a6db490c8f5d2217 Added Reference https://github.com/protobufjs/protobuf.js/commit/fa5c73add738ceb471e74da8cc2f3727c3d0a69f Added Reference https://github.com/protobufjs/protobuf.js/pull/2352 Added Reference https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v7.6.5 Added Reference https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v8.6.6 Added Reference https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-j3f2-48v5-ccww