---
title: "CVE-2026-41242: Arbitrary code execution in protobufjs"
url: https://erroneo.us/security/cve/CVE-2026-41242/
description: "CVE-2026-41242 (protobufjs (npm)): protobufjs compiles protobuf definitions into JavaScript (JS) functions. In versions prior to 8.0.1 and 7.5.5, attackers…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-04-18
date_modified: 2026-09-09
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-41242"
kev: false
cvss: 9.4
epss: 0.0099
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-41242: Arbitrary code execution in protobufjs

**Signal:** Critical, preconditions apply. Severe if exploited, but exploitation needs conditions that may not apply to you. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 1.0% , percentile 62: FIRST’s model estimates a 1.0% chance of exploitation activity in the next 30 days, higher than 62% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Needs an account (low (any account)). Exposure depends on who can log in.
- Only applies if your dependency tree includes protobufjs (npm) >= 8.0.0, < 8.0.1, fixed in 8.0.1 ; protobufjs (npm) < 7.5.5, fixed in 7.5.5 . Check your lockfile, including transitive dependencies.

## What it is

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.

## Affected packages

- npm `protobufjs` >= 8.0.0, < 8.0.1 → fixed: 8.0.1
- npm `protobufjs` < 7.5.5 → fixed: 7.5.5

## Affected products (CVE record)

- protobufjs protobuf.js: < 7.5.5, >= 8.0.0-experimental, < 8.0.1

## Severity

- GitHub_M CVSS 4.0: 9.4 `CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H`
- redhat-SADP CVSS 3.1: 8.8 `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`
- GitHub CVSS 4.0: 9.4 `CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.99% probability of exploitation activity in the next 30 days; percentile 62.

## Sources

- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:21338)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:26234)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:24977)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:37275)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:62260)
- [GitHub Advisory GHSA-xq3m-2v4x-88gg](https://github.com/advisories/GHSA-xq3m-2v4x-88gg)
- [CVE.org record CVE-2026-41242](https://www.cve.org/CVERecord?id=CVE-2026-41242)
- [NVD entry CVE-2026-41242](https://nvd.nist.gov/vuln/detail/CVE-2026-41242)
- [github.com](https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-xq3m-2v4x-88gg)
- [github.com](https://github.com/protobufjs/protobuf.js/commit/535df444ac060243722ac5d672db205e5c531d75)
- [github.com](https://github.com/protobufjs/protobuf.js/commit/ff7b2afef8754837cc6dc64c864cd111ab477956)
- [github.com](https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v7.5.5)
- [github.com](https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v8.0.1)
- [access.redhat.com](https://access.redhat.com/security/cve/CVE-2026-41242)
- [RHBZ#2459442](https://bugzilla.redhat.com/show_bug.cgi?id=2459442)
- [security.access.redhat.com](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-41242.json)

---
Source page: https://erroneo.us/security/cve/CVE-2026-41242/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt