locutusjs locutus up to 2.0.38 prototype pollution

Summaryinfo

A vulnerability identified as problematic has been detected in locutusjs locutus up to 2.0.38. This affects an unknown part. The manipulation leads to prototype pollution. This vulnerability is listed as CVE-2026-25521. The attack must be carried out locally. There is no available exploit. You should upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in locutusjs locutus up to 2.0.38. This issue affects some unknown functionality. The manipulation with an unknown input leads to a prototype pollution vulnerability. Using CWE to declare the problem leads to CWE-1321. 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. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

Locutus brings stdlibs of other programming languages to JavaScript for educational purposes. In versions from 2.0.12 to before 2.0.39, a prototype pollution vulnerability exists in locutus. Despite a previous fix that attempted to mitigate prototype pollution by checking whether user input contained a forbidden key, it is still possible to pollute Object.prototype via a crafted input using String.prototype. This issue has been patched in version 2.0.39.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-25521 since 02/02/2026. The exploitation is known to be easy. Attacking locally is a requirement. The technical details are unknown and an exploit is not publicly available. The attack technique deployed by this issue is T1059 according to MITRE ATT&CK.

Upgrading to version 2.0.39 eliminates this vulnerability. Applying the patch 042af9ca7fde2ff599120783e720a17f335bb01c is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-5340). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Vendor

• locutusjs

Name

• locutus

Version

• 2.0.0
• 2.0.1
• 2.0.2
• 2.0.3
• 2.0.4
• 2.0.5
• 2.0.6
• 2.0.7
• 2.0.8
• 2.0.9
• 2.0.10
• 2.0.11
• 2.0.12
• 2.0.13
• 2.0.14
• 2.0.15
• 2.0.16
• 2.0.17
• 2.0.18
• 2.0.19
• 2.0.20
• 2.0.21
• 2.0.22
• 2.0.23
• 2.0.24
• 2.0.25
• 2.0.26
• 2.0.27
• 2.0.28
• 2.0.29
• 2.0.30
• 2.0.31
• 2.0.32
• 2.0.33
• 2.0.34
• 2.0.35
• 2.0.36
• 2.0.37
• 2.0.38

License

• open-source

Website

• Product: https://github.com/locutusjs/locutus/

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Be aware that VulDB is the high quality source for vulnerability data.

Discussion