CVE-2026-54335: @feathersjs/commons Prototype Pollution Vulnerability

LOW
Advisory Identifier: GHSA-28xv-ph75-77wh
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CVSS 3.7
CWE-1321
Published
Advisory Summary

CVE-2026-54335 is a LOW (CVSS 3.7) prototype pollution vulnerability (CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')) affecting @feathersjs/commons libraries in the npm ecosystem. The issue involves prototype pollution in @feathersjs/commons _.merge via json-parsed __proto__. Remediation is available by upgrading affected packages to version 5.0.45.

CVE-2026-54335 at a Glance

CVE Identifier CVE-2026-54335
GHSA Identifier GHSA-28xv-ph75-77wh
Severity LOW
CVSS v3.1 Base Score 3.7
CWE Classification CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Affected Product @feathersjs/commons
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 3.7

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

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

How to Fix CVE-2026-54335

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

@feathersjs/commons fixed: 5.0.45 
npm install @feathersjs/commons@5.0.45
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 @feathersjs/commons

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-54335, inspect your project dependencies using npm:

npm ls @feathersjs/commons

Analyze the terminal output to locate any version of @feathersjs/commons in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 5.0.45), your application is affected.

Note: The npm ls @feathersjs/commons 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 @feathersjs/commons, 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

### Impact The `_.merge(target, source)` utility exported by `@feathersjs/commons` recursively merges `source` into `target` by iterating `Object.keys(source)`. When `source` was produced by `JSON.parse` and contains a `__proto__` (or `constructor` / `prototype`) key, that key is returned as an own-enumerable property. The recursive merge then resolves `target['__proto__']` to `Object.prototype` and writes the attacker-supplied properties onto it, polluting the prototype for all plain objects in the process for the lifetime of the Node process. **Scope of real-world risk is limited.** No first-party Feathers package routes input — trusted or untrusted — through `commons._.merge`. The `@feathersjs/authentication` package, which does merge request-influenced data, uses `lodash/merge` (prototype-pollution-safe since 4.17.12), not this utility. Exploitation therefore requires a downstream plugin or application to pass JSON-parsed, attacker-controlled input directly through the exported `_.merge`. ### Patches Fixed in `@feathersjs/commons@5.0.45`. The fix skips `__proto__`, `constructor`, and `prototype` keys during iteration — the standard remediation used by lodash and others. ### Workarounds Avoid passing JSON-parsed untrusted input through `commons._.merge`. Freezing `Object.prototype` or validating/sanitizing keys upstream also mitigates. ### Credit Reported responsibly by Andrew Ridings (@ridingsa).

CVE-2026-54335 Affected @feathersjs/commons Versions

1 component(s)
Fixed Versions:
5.0.45
Product / Package Ecosystem Affected Versions Fixed Version
@feathersjs/commons
npm/@feathersjs/commons
npm
< 5.0.45
5.0.45

References

GitHub Advisory / Wiki ADVISORY
https://github.com/feathersjs/feathers/security/advisories/GHSA-28xv-ph75-77wh
@feathersjs/commons Source Repository REPOSITORY
https://github.com/feathersjs/feathers/pull/3690
Security Fix Commit FIX COMMIT
https://github.com/feathersjs/feathers/commit/28b3c03c63bdbff53115fdaa46c56980e7942acc
@feathersjs/commons Source Repository REPOSITORY
https://github.com/feathersjs/feathers
@feathersjs/commons Release RELEASE
https://github.com/feathersjs/feathers/releases/tag/v5.0.45

Frequently Asked Questions

What is CVE-2026-54335?
CVE-2026-54335 is a security vulnerability in @feathersjs/commons involving Prototype pollution in @feathersjs/commons _.merge via JSON-parsed __proto__ under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution').
Which @feathersjs/commons versions are affected?
Affected versions include releases prior to 5.0.45 across affected packages: @feathersjs/commons.
What version fixes CVE-2026-54335?
Upgrading to 5.0.45 (or the latest patched release for your respective branch) resolves the vulnerability.
Is @feathersjs/commons affected?
Yes, @feathersjs/commons is affected in releases prior to 5.0.45. Upgrade your dependency to 5.0.45 or later.
What is the CVSS score of CVE-2026-54335?
CVE-2026-54335 has a CVSS v3.1 base score of 3.7 (LOW) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N.
What CWE is associated with CVE-2026-54335?
CVE-2026-54335 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-2026-54335?
Run the dependency tree command: 'npm ls @feathersjs/commons'. 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-28xv-ph75-77wh",
  "modified" : "2026-07-14T19:40:05Z",
  "published" : "2026-07-14T19:40:05Z",
  "aliases" : [ "CVE-2026-54335" ],
  "summary" : "Prototype pollution in @feathersjs/commons _.merge via JSON-parsed __proto__",
  "details" : "### Impact\n\nThe `_.merge(target, source)` utility exported by `@feathersjs/commons` recursively merges `source` into `target` by iterating `Object.keys(source)`. When `source` was produced by `JSON.parse` and contains a `__proto__` (or `constructor` / `prototype`) key, that key is returned as an own-enumerable property. The recursive merge then resolves `target['__proto__']` to `Object.prototype` and writes the attacker-supplied properties onto it, polluting the prototype for all plain objects in the process for the lifetime of the Node process.\n\n**Scope of real-world risk is limited.** No first-party Feathers package routes input — trusted or untrusted — through `commons._.merge`. The `@feathersjs/authentication` package, which does merge request-influenced data, uses `lodash/merge` (prototype-pollution-safe since 4.17.12), not this utility. Exploitation therefore requires a downstream plugin or application to pass JSON-parsed, attacker-controlled input directly through the exported `_.merge`.\n\n### Patches\n\nFixed in `@feathersjs/commons@5.0.45`. The fix skips `__proto__`, `constructor`, and `prototype` keys during iteration — the standard remediation used by lodash and others.\n\n### Workarounds\n\nAvoid passing JSON-parsed untrusted input through `commons._.merge`. Freezing `Object.prototype` or validating/sanitizing keys upstream also mitigates.\n\n### Credit\n\nReported responsibly by Andrew Ridings (@ridingsa).",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@feathersjs/commons"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "5.0.45"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 5.0.44"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/feathersjs/feathers/security/advisories/GHSA-28xv-ph75-77wh"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/feathersjs/feathers/pull/3690"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/feathersjs/feathers/commit/28b3c03c63bdbff53115fdaa46c56980e7942acc"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/feathersjs/feathers"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/feathersjs/feathers/releases/tag/v5.0.45"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1321" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-14T19:40:05Z",
    "nvd_published_at" : null
  }
}