CVE-2026-2950: Lodash Lodash Vulnerable To Prototype Pollution Vulnerability

MODERATE
Advisory Identifier: GHSA-f23m-r3pf-42rh
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CVSS 6.5
CWE-1321
Published
Advisory Summary

CVE-2026-2950 is a MODERATE (CVSS 6.5) lodash vulnerable to prototype pollution vulnerability (CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')) affecting Lodash libraries in the npm ecosystem. The issue involves lodash vulnerable to prototype pollution via array path bypass in `_.unset` and `_.omit`. Remediation is available by upgrading affected packages to version 4.18.0.

CVE-2026-2950 at a Glance

CVE Identifier CVE-2026-2950
GHSA Identifier GHSA-f23m-r3pf-42rh
Severity MODERATE
CVSS v3.1 Base Score 6.5
CWE Classification CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Affected Product Lodash
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:N/I:L/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 None (C:N)
Integrity Low (I:L)
Availability Low (A:L)

How to Fix CVE-2026-2950

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

lodash fixed: 4.18.0 
npm install lodash@4.18.0
lodash-es fixed: 4.18.0 
npm install lodash-es@4.18.0
lodash-amd fixed: 4.18.0 
npm install lodash-amd@4.18.0
lodash.unset fixed: 4.18.0 
npm install lodash.unset@4.18.0
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 lodash

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-2950, inspect your project dependencies using npm:

npm ls lodash

Analyze the terminal output to locate any version of Lodash in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 4.18.0), your application is affected.

Note: The npm ls lodash 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 Lodash, 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 Lodash versions 4.17.23 and earlier are vulnerable to prototype pollution in the `_.unset` and `_.omit` functions. The fix for [CVE-2025-13465](https://github.com/lodash/lodash/security/advisories/GHSA-xxjr-mmjv-4gpg) only guards against string key members, so an attacker can bypass the check by passing array-wrapped path segments. This allows deletion of properties from built-in prototypes such as `Object.prototype`, `Number.prototype`, and `String.prototype`. The issue permits deletion of prototype properties but does not allow overwriting their original behavior. ### Patches This issue is patched in 4.18.0. ### Workarounds None. Upgrade to the patched version.

CVE-2026-2950 Affected Lodash Versions

4 component(s)
Fixed Versions:
4.18.0
Product / Package Ecosystem Affected Versions Fixed Version
lodash
npm/lodash
npm
< 4.18.0
4.18.0
lodash-es
npm/lodash-es
npm
< 4.18.0
4.18.0
lodash-amd
npm/lodash-amd
npm
< 4.18.0
4.18.0
lodash.unset
npm/lodash.unset
npm
≥ 4.0.0
< 4.18.0
4.18.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/lodash/lodash/security/advisories/GHSA-f23m-r3pf-42rh
GitHub Advisory / Wiki ADVISORY
https://github.com/lodash/lodash/security/advisories/GHSA-xxjr-mmjv-4gpg
NVD — CVE-2026-2950 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-2950
Lodash Source Repository REPOSITORY
https://github.com/lodash/lodash

Frequently Asked Questions

What is CVE-2026-2950?
CVE-2026-2950 is a security vulnerability in Lodash involving lodash vulnerable to Prototype Pollution via array path bypass in `_.unset` and `_.omit` under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution').
Which Lodash versions are affected?
Affected versions include releases prior to 4.18.0 across affected packages: lodash, lodash-es, lodash-amd, lodash.unset.
What version fixes CVE-2026-2950?
Upgrading to 4.18.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is lodash affected?
Yes, lodash is affected in releases prior to 4.18.0. Upgrade your dependency to 4.18.0 or later.
Is lodash-es affected?
Yes, lodash-es is affected in releases prior to 4.18.0. Upgrade your dependency to 4.18.0 or later.
What is the CVSS score of CVE-2026-2950?
CVE-2026-2950 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:N/I:L/A:L.
What CWE is associated with CVE-2026-2950?
CVE-2026-2950 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-2026-2950?
Run the dependency tree command: 'npm ls lodash'. 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-f23m-r3pf-42rh",
  "modified" : "2026-04-01T23:50:27Z",
  "published" : "2026-04-01T23:50:27Z",
  "aliases" : [ "CVE-2026-2950" ],
  "summary" : "lodash vulnerable to Prototype Pollution via array path bypass in `_.unset` and `_.omit`",
  "details" : "### Impact\n\nLodash versions 4.17.23 and earlier are vulnerable to prototype pollution in the `_.unset` and `_.omit` functions. The fix for [CVE-2025-13465](https://github.com/lodash/lodash/security/advisories/GHSA-xxjr-mmjv-4gpg) only guards against string key members, so an attacker can bypass the check by passing array-wrapped path segments. This allows deletion of properties from built-in prototypes such as `Object.prototype`, `Number.prototype`, and `String.prototype`.\n\nThe issue permits deletion of prototype properties but does not allow overwriting their original behavior.\n\n### Patches\n\nThis issue is patched in 4.18.0.\n\n### Workarounds\n\nNone. Upgrade to the patched version.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L"
  } ],
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    "database_specific" : {
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    },
    "ranges" : [ {
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      "events" : [ {
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      } ]
    } ]
  } ],
  "references" : [ {
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    "url" : "https://github.com/lodash/lodash/security/advisories/GHSA-f23m-r3pf-42rh"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/lodash/lodash/security/advisories/GHSA-xxjr-mmjv-4gpg"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-2950"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/lodash/lodash"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1321" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-01T23:50:27Z",
    "nvd_published_at" : "2026-03-31T20:16:26Z"
  }
}