CVE-2026-41242 protobufjs has an arbitrary code execution issue
Attackers can inject arbitrary code into protobuf definitions that executes during object decoding, allowing remote code execution in applications using the library.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-41242?
CVE-2026-41242 is a critical code injection vulnerability in protobufjs protobuf.js, published on 18 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
protobufjs compiles protobuf definitions into JavaScript (JS) functions. In versions prior to 8.0.1 and 7.5.5, attackers can inject arbitrary code in the "type" fields of protobuf definitions, which will then execute during object decoding using that definition. Versions 8.0.1 and 7.5.5 patch the issue.
Weakness: CWE-94
Which versions are affected by CVE-2026-41242?
4 open source packages ship an affected version, including protobufjs. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
protobufjs npm | All versions | 7.5.5 |
protobufjs npm | All versions | 7.5.5 |
protobufjs npm | From 8.0.0 | 8.0.1 |
protobufjs npm | From 8.0.0 | 8.0.1 |
Products include Protobufjs Project Protobufjs.
How do I fix CVE-2026-41242?
Upgrade protobufjs to a fixed version for your release line: 7.5.5 or 8.0.1.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
Is CVE-2026-41242 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-41242 exists.
Public exploit code: 2 proofs of concept on GitHub.
Other vulnerabilities in protobufjs protobuf.js
- CVE-2023-36665 protobufjs Prototype Pollution vulnerability
- CVE-2022-25878 Prototype Pollution
- CVE-2026-44291 protobufjs: Code generation gadget after prototype pollution
- CVE-2026-44293 protobufjs: Code injection through bytes field defaults in generated toObject code
- CVE-2026-48712 protobufjs: Denial of service through unbounded Any expansion during JSON conversion
Sources
Also known as CLEANSTART-2026-BY01159, CLEANSTART-2026-XC94160, CLSA-2026-1778114667, ECHO-bb3f-55f6-c0f6, GHSA-xq3m-2v4x-88gg, MINI-26v9-9486-q27w and 14 more.