GHSA-f23m-r3pf-42rh CVE-2026-2950
lodash vulnerable to Prototype Pollution via array path bypass in `_.unset` and `_.omit`
- Severity
- 6.5 / 10
- Medium · CVSS 3.1
- Exploit chance (EPSS)
- 0.34%
- Chance of exploitation in the next 30 days. Higher than 27.17% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-1321 Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
- Fix
- Available
- 4 packages have a fixed version
Description
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 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.
Affected versions
npm
| Package | Vulnerable | Fixed in |
|---|---|---|
| lodash | <= 4.17.23 |
No fix yet |
| lodash | < 4.18.0 |
4.18.0 |
| lodash-amd | <= 4.17.23 |
No fix yet |
| lodash-amd | < 4.18.0 |
4.18.0 |
| lodash-es | <= 4.17.23 |
No fix yet |
| lodash-es | < 4.18.0 |
4.18.0 |
| lodash.unset | >= 4.0.0, < 4.18.0 |
4.18.0 |
| lodash.unset | >= 4.0.0, < 4.18.0 |
4.18.0 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
lodash npm → 4.18.0
- npm
npm install lodash@4.18.0- yarn
yarn add lodash@4.18.0- pnpm
pnpm add lodash@4.18.0
lodash-amd npm → 4.18.0
- npm
npm install lodash-amd@4.18.0- yarn
yarn add lodash-amd@4.18.0- pnpm
pnpm add lodash-amd@4.18.0
lodash-es npm → 4.18.0
- npm
npm install lodash-es@4.18.0- yarn
yarn add lodash-es@4.18.0- pnpm
pnpm add lodash-es@4.18.0
lodash.unset npm → 4.18.0
- npm
npm install lodash.unset@4.18.0- yarn
yarn add lodash.unset@4.18.0- pnpm
pnpm add lodash.unset@4.18.0
Severity breakdown
CVSS 3.1 6.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- Low
- Availability
- Low
Weakness
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 to prevent it
- Implementation: By freezing the object prototype first (for example, Object.freeze(Object.prototype)), modification of the prototype becomes impossible.
- Architecture and Design: By blocking modifications of attributes that resolve to object prototype, such as proto or prototype, this weakness can be mitigated.
- Implementation: When handling untrusted objects, validating using a schema can be used.
- Implementation: By using an object without prototypes (via Object.create(null) ), adding object prototype attributes by accessing the prototype via the special attributes becomes impossible, mitigating this weakness.
- Implementation: Map can be used instead of objects in most cases. If Map methods are used instead of object attributes, it is not possible to access the object prototype or modify it.
References
Advisories
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-r5fr-rjxr-66jc lodash vulnerable to Code Injection via `_.template` imports key names | Critical | Also affects lodash |
| GHSA-xxjr-mmjv-4gpg Lodash has Prototype Pollution Vulnerability in `_.unset` and `_.omit` functions | Medium | Also affects lodash |
| GHSA-29mw-wpgm-hmr9 Regular Expression Denial of Service (ReDoS) in lodash | Medium | Also affects lodash |
| GHSA-35jh-r3h4-6jhm Command Injection in lodash | High | Also affects lodash |
| GHSA-p6mc-m468-83gw Prototype Pollution in lodash | High | Also affects lodash |
| GHSA-x5rq-j2xg-h7qm Regular Expression Denial of Service (ReDoS) in lodash | Medium | Also affects lodash |
| GHSA-jf85-cpcp-j695 Prototype Pollution in lodash | Critical | Also affects lodash |
| GHSA-4xc9-xhrj-v574 Prototype Pollution in lodash | High | Also affects lodash |
Credits: Haruna38, UlisesGascon, backuardo, falsyvalues, jdalton, jonchurch, maru1009, ott3r07, shpik-kr, zolbooo
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