CVE-2026-44291 protobufjs: Code generation gadget after prototype pollution
Attackers can execute arbitrary code via prototype pollution in protobufjs by injecting malicious strings into generated JavaScript functions.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-44291?
CVE-2026-44291 is a high-severity code injection vulnerability in protobufjs protobuf.js, published on 13 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
protobufjs compiles protobuf definitions into JavaScript (JS) functions. Prior to 7.5.6 and 8.0.2, protobufjs used plain objects with inherited prototypes for internal type lookup tables used by generated encode and decode functions. If Object.prototype had already been polluted, those lookup tables could resolve attacker-controlled inherited properties as valid protobuf type information. This could cause attacker-controlled strings to be emitted into generated JavaScript code. This vulnerability is fixed in 7.5.6 and 8.0.2.
Weakness: CWE-94
Which versions are affected by CVE-2026-44291?
4 open source packages ship an affected version, including protobufjs. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
protobufjs npm | All versions | 7.5.6 |
protobufjs npm | All versions | 7.5.6 |
protobufjs npm | From 8.0.0 | 8.0.2 |
protobufjs npm | From 8.0.0 | 8.0.2 |
Products include Protobufjs Project Protobufjs.
How do I fix CVE-2026-44291?
Upgrade protobufjs to a fixed version for your release line: 7.5.6 or 8.0.2.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
Is CVE-2026-44291 being exploited?
There is no known exploitation of CVE-2026-44291 in the wild and no public exploit code.
Other vulnerabilities in protobufjs protobuf.js
- CVE-2023-36665 protobufjs Prototype Pollution vulnerability
- CVE-2026-41242 protobufjs has an arbitrary code execution issue
- CVE-2022-25878 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-JH02542, CLEANSTART-2026-OR18491, CLEANSTART-2026-QG09459, ECHO-3792-9b0f-a42e, GHSA-75px-5xx7-5xc7, MINI-5f8r-wjwf-pvpg and 16 more.