# CVE-2026-44292: protobufjs prototype pollution in generated message constructors

Source: https://junglewise.ai/threats/cve-2026-44292-protobuf-js-prototype-injection-in-generated-message-constructors  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-13. Updated: 2026-05-14  
License: CC BY 4.0 with a link back

CVE-2026-44292 · Severity: medium · CVSS 5.3 · Published 2026-05-13

protobufjs is a library used to handle data serialization in JavaScript applications. A vulnerability in how it creates new data objects allows an attacker to manipulate the internal structure of those objects if they can provide the input data (such as through a malicious JSON file). While this does not affect the entire system, it can lead to unexpected behavior, data integrity issues, or security bypasses depending on how the application uses those specific objects.

Technologies: [protobufjs (npm)](https://junglewise.ai/threats/technologies/protobufjs). Vendors: [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is CVE-2026-44292 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-44292 being exploited in the wild.

**How severe is CVE-2026-44292?** Medium severity, with a CVSS score of 5.3, published 13 May 2026.

**Which products and versions are affected?** protobufjs (npm) SEMVER:introduced=0,fixed=7.5.6.

**Is there a fix for CVE-2026-44292?** Yes. protobufjs (npm): upgrade to 7.5.6 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-44292 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-44292?** Check whether you run protobufjs (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- protobufjs (npm): upgrade to 7.5.6 or later

  ```sh
  npm install protobufjs@7.5.6
  ```


## Technical details

A prototype pollution vulnerability (CWE-1321) exists in protobufjs due to improper filtering of the '__proto__' key during object construction. When the library generates message constructors, it copies enumerable properties from a provided object without validation. An attacker who can influence the properties object (e.g., via parsed JSON) can inject a '__proto__' property to alter the prototype of that specific message instance. This is a per-instance injection and does not affect the global Object.prototype. The vulnerability is reachable over the network if the application processes untrusted input to create protobuf messages. It has been patched in versions 7.5.6 and 8.0.2.

## Affected products

- protobufjs project protobufjs < 7.5.6, >= 8.0.0 < 8.0.2

## Identifiers

- CVE-2026-44292
- GHSA-fx83-v9x8-x52w

## Timeline

- 2026-05-12: advisory: GitHub Security Advisory published
- 2026-05-13: disclosed: NVD publication date

## References

- [https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-fx83-v9x8-x52w](https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-fx83-v9x8-x52w)

## Related threats

- [protobufjs prototype mutation in Text Format string map parsing](https://junglewise.ai/threats/cve-2026-59876-protobufjs-prototype-pollution-in-text-format-extension)
- [protobufjs infinite loop in .proto option parsing](https://junglewise.ai/threats/cve-2026-59877-protobufjs-infinite-loop-in-proto-option-parsing)
- [protobufjs memory amplification via unknown field preservation](https://junglewise.ai/threats/cve-2026-54270-protobufjs-memory-amplification-via-unknown-field-preservation)
- [protobufjs property shadowing and uncontrolled recursion](https://junglewise.ai/threats/cve-2026-54269-protobufjs-property-shadowing-and-uncontrolled-recursion)
- [protobufjs uncontrolled recursion in JSON conversion](https://junglewise.ai/threats/cve-2026-48712-protobufjs-uncontrolled-recursion-in-json-conversion)