CVE-2026-5758: Protocol buffers schema Mafintosh's Protocol-buffers-schema Is Vulnerable To Vulnerability

MODERATE
Advisory Identifier: GHSA-j452-xhg8-qg39
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CVSS 6.5
CWE-1321
Published
Advisory Summary

CVE-2026-5758 is a MODERATE (CVSS 6.5) mafintosh's protocol-buffers-schema is vulnerable to vulnerability (CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')) affecting Protocol buffers schema libraries in the npm ecosystem. The issue involves mafintosh's protocol-buffers-schema is vulnerable to prototype pollution. Remediation is available by upgrading affected packages to version 3.6.1.

CVE-2026-5758 at a Glance

CVE Identifier CVE-2026-5758
GHSA Identifier GHSA-j452-xhg8-qg39
Severity MODERATE
CVSS v3.1 Base Score 6.5
CWE Classification CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Affected Product Protocol buffers schema
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 6.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality Low (C:L)
Integrity None (I:N)
Availability Low (A:L)

How to Fix CVE-2026-5758

To remediate this vulnerability, upgrade all affected Protocol buffers schema dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

protocol-buffers-schema fixed: 3.6.1 
npm install protocol-buffers-schema@3.6.1
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls protocol-buffers-schema

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-5758, inspect your project dependencies using npm:

npm ls protocol-buffers-schema

Analyze the terminal output to locate any version of Protocol buffers schema in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.6.1), your application is affected.

Note: The npm ls protocol-buffers-schema command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution'), where the product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype. In Protocol buffers schema, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

JavaScript is vulnerable to prototype pollution in Mafintosh's protocol-buffers-schema Version 3.6.0, where an attacker may alter the application logic, bypass security checks, cause a DoS or achieve remote code execution.

CVE-2026-5758 Affected Protocol buffers schema Versions

1 component(s)
Fixed Versions:
3.6.1
Product / Package Ecosystem Affected Versions Fixed Version
protocol-buffers-schema
npm/protocol-buffers-schema
npm
< 3.6.1
3.6.1

References

NVD — CVE-2026-5758 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-5758
Protocol buffers schema Source Repository REPOSITORY
https://github.com/mafintosh/protocol-buffers-schema/pull/70
Protocol buffers schema Source Repository REPOSITORY
https://github.com/mafintosh/protocol-buffers-schema
morielharush.github.io/2026/04/12/cve-2026... WEB
https://morielharush.github.io/2026/04/12/cve-2026-5758-protocol-buffers-schema-prototype-pollution

Frequently Asked Questions

What is CVE-2026-5758?
CVE-2026-5758 is a security vulnerability in Protocol buffers schema involving Mafintosh's protocol-buffers-schema is vulnerable to prototype pollution under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution').
Which Protocol buffers schema versions are affected?
Affected versions include releases prior to 3.6.1 across affected packages: protocol-buffers-schema.
What version fixes CVE-2026-5758?
Upgrading to 3.6.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is protocol-buffers-schema affected?
Yes, protocol-buffers-schema is affected in releases prior to 3.6.1. Upgrade your dependency to 3.6.1 or later.
What is the CVSS score of CVE-2026-5758?
CVE-2026-5758 has a CVSS v3.1 base score of 6.5 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L.
What CWE is associated with CVE-2026-5758?
CVE-2026-5758 is classified under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') (The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.).
How can I check npm dependencies for CVE-2026-5758?
Run the dependency tree command: 'npm ls protocol-buffers-schema'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-j452-xhg8-qg39",
  "modified" : "2026-04-16T21:33:53Z",
  "published" : "2026-04-15T18:31:58Z",
  "aliases" : [ "CVE-2026-5758" ],
  "summary" : "Mafintosh's protocol-buffers-schema is vulnerable to prototype pollution",
  "details" : "JavaScript is vulnerable to prototype pollution in Mafintosh's protocol-buffers-schema Version 3.6.0, where an attacker may alter the application logic, bypass security checks, cause a DoS or achieve remote code execution.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "protocol-buffers-schema"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.6.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-5758"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mafintosh/protocol-buffers-schema/pull/70"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/mafintosh/protocol-buffers-schema"
  }, {
    "type" : "WEB",
    "url" : "https://morielharush.github.io/2026/04/12/cve-2026-5758-protocol-buffers-schema-prototype-pollution"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1321" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-16T21:33:53Z",
    "nvd_published_at" : "2026-04-15T18:17:24Z"
  }
}