CVE-2026-25521 Locutus is vulnerable to Prototype Pollution
Attackers can pollute Object.prototype via crafted input, potentially leading to code execution or privilege escalation in applications using the Locutus library.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-25521?
CVE-2026-25521 is a critical vulnerability in locutusjs locutus, published on 4 Feb 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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.
Which versions are affected by CVE-2026-25521?
2 open source packages ship an affected version, including locutus. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
locutus npm | From 2.0.12 | 2.0.39 |
locutus npm | From 2.0.12 | 2.0.39 |
Products include Locutus Locutus.
How do I fix CVE-2026-25521?
Upgrade locutus to 2.0.39 or later.
Is CVE-2026-25521 being exploited?
There is no known exploitation of CVE-2026-25521 in the wild and no public exploit code.
Other vulnerabilities in locutusjs locutus
- CVE-2026-32304 Locutus: RCE via unsanitized input in create_function()
- CVE-2020-7719 Prototype Pollution
- CVE-2026-29091 Locutus: Remote Code Execution (RCE) in locutus call_user_func_array due to Code Injection
- CVE-2026-33993 Locutus has Prototype Pollution via __proto__ Key Injection in unserialize()
- CVE-2026-33994 Locutus Prototype Pollution due to incomplete fix for CVE-2026-25521
Sources
Also known as GHSA-rxrv-835q-v5mh.