CVE-2026-44293: Protobufjs Code Injection Through Bytes Field Vulnerability

HIGH
Advisory Identifier: GHSA-66ff-xgx4-vchm
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CWE-94
Published
Advisory Summary

CVE-2026-44293 is a HIGH code injection through bytes field vulnerability (CWE-94: Improper Control of Generation of Code ('Code Injection')) affecting Protobufjs libraries in the npm ecosystem. The issue involves code injection through bytes field defaults in generated toobject code. Remediation is available by upgrading affected packages to version 7.5.6, 8.0.2.

CVE-2026-44293 at a Glance

CVE Identifier CVE-2026-44293
GHSA Identifier GHSA-66ff-xgx4-vchm
Severity HIGH
CVSS v3.1 Base Score N/A
CWE Classification CWE-94: Improper Control of Generation of Code ('Code Injection')
Affected Product Protobufjs
Package Ecosystem npm
Published Date
Last Updated

How to Fix CVE-2026-44293

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

protobufjs fixed: 7.5.6 
npm install protobufjs@7.5.6
protobufjs fixed: 8.0.2 
npm install protobufjs@8.0.2
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 protobufjs

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-44293, inspect your project dependencies using npm:

npm ls protobufjs

Analyze the terminal output to locate any version of Protobufjs in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 7.5.6), your application is affected.

Note: The npm ls protobufjs 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-94: Improper Control of Generation of Code ('Code Injection'), where the product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment. In Protobufjs, 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

## Summary protobufjs generated JavaScript for `toObject` conversion could include an unsafe expression derived from a schema-controlled `bytes` field default value. A crafted descriptor with a non-string default value for a `bytes` field could cause attacker-controlled code to be emitted into the generated conversion function. ## Impact An attacker who can provide or influence a protobuf descriptor may be able to execute arbitrary JavaScript in the context of the process using protobufjs. This requires the application to load an attacker-controlled schema or descriptor and then convert a message of the affected type with defaults enabled. Applications that only use trusted, application-defined schemas are not directly affected by this issue. ## Preconditions - The application must allow an attacker to control or influence a protobuf JSON descriptor or equivalent reflected schema. - The descriptor must define a `bytes` field with an attacker-controlled default value. - The application must call `toObject` with defaults enabled for the affected type. ## Workarounds Do not load protobuf schemas or JSON descriptors from untrusted sources with affected versions. If untrusted schemas must be accepted, validate or restrict field options before loading them and run schema processing in an isolated environment.

CVE-2026-44293 Affected Protobufjs Versions

2 component(s)
Fixed Versions:
7.5.68.0.2
Product / Package Ecosystem Affected Versions Fixed Version
protobufjs
npm/protobufjs
npm
< 7.5.6
7.5.6
protobufjs
npm/protobufjs
npm
≥ 8.0.0
< 8.0.2
8.0.2

References

GitHub Advisory / Wiki ADVISORY
https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-66ff-xgx4-vchm
Protobufjs Source Repository REPOSITORY
https://github.com/protobufjs/protobuf.js
Protobufjs Release RELEASE
https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v7.5.6
Protobufjs Release RELEASE
https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v8.0.2

Frequently Asked Questions

What is CVE-2026-44293?
CVE-2026-44293 is a security vulnerability in Protobufjs involving Code injection through bytes field defaults in generated toObject code under CWE-94: Improper Control of Generation of Code ('Code Injection').
Which Protobufjs versions are affected?
Affected versions include releases prior to 7.5.6, 8.0.2 across affected packages: protobufjs.
What version fixes CVE-2026-44293?
Upgrading to 7.5.6, 8.0.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is protobufjs affected?
Yes, protobufjs is affected in releases prior to 7.5.6, 8.0.2. Upgrade your dependency to 7.5.6, 8.0.2 or later.
What CWE is associated with CVE-2026-44293?
CVE-2026-44293 is classified under CWE-94: Improper Control of Generation of Code ('Code Injection') (The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.).
How can I check npm dependencies for CVE-2026-44293?
Run the dependency tree command: 'npm ls protobufjs'. 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-66ff-xgx4-vchm",
  "modified" : "2026-05-12T15:06:13Z",
  "published" : "2026-05-12T15:06:13Z",
  "aliases" : [ "CVE-2026-44293" ],
  "summary" : "protobuf.js: Code injection through bytes field defaults in generated toObject code",
  "details" : "## Summary\n\nprotobufjs generated JavaScript for `toObject` conversion could include an unsafe expression derived from a schema-controlled `bytes` field default value. A crafted descriptor with a non-string default value for a `bytes` field could cause attacker-controlled code to be emitted into the generated conversion function.\n\n## Impact\n\nAn attacker who can provide or influence a protobuf descriptor may be able to execute arbitrary JavaScript in the context of the process using protobufjs.\n\nThis requires the application to load an attacker-controlled schema or descriptor and then convert a message of the affected type with defaults enabled. Applications that only use trusted, application-defined schemas are not directly affected by this issue.\n\n## Preconditions\n\n- The application must allow an attacker to control or influence a protobuf JSON descriptor or equivalent reflected schema.\n- The descriptor must define a `bytes` field with an attacker-controlled default value.\n- The application must call `toObject` with defaults enabled for the affected type.\n\n## Workarounds\n\nDo not load protobuf schemas or JSON descriptors from untrusted sources with affected versions. If untrusted schemas must be accepted, validate or restrict field options before loading them and run schema processing in an isolated environment.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "protobufjs"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "7.5.6"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 7.5.5"
    }
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "protobufjs"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "8.0.0"
      }, {
        "fixed" : "8.0.2"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 8.0.1"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-66ff-xgx4-vchm"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/protobufjs/protobuf.js"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v7.5.6"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v8.0.2"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-94" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-12T15:06:13Z",
    "nvd_published_at" : null
  }
}