---
id: "CVE-2026-65843"
page: "https://infrastack.ai/live/CVE-2026-65843"
kind: "vulnerability"
aliases: ["CVE-2026-65843"]
title: "sync-rpc: attacker can run arbitrary JavaScript files on the server"
severity: "high"
cvss: 8.7
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["node", "package", "self-hosted", "sync-rpc"]
not_affected_if: ["port-firewalled", "version-1.3.7-or-later"]
published_at: "2026-11-11T19:17:44+00:00"
first_seen_at: "2026-11-11T19:28:48+00:00"
updated_at: "2026-11-11T19:29:50+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-65843", "first_seen_at": "2026-11-11T19:28:48+00:00"}]
exploit_sources: []
---

# sync-rpc: attacker can run arbitrary JavaScript files on the server

Link for people: https://infrastack.ai/live/CVE-2026-65843 (this .md is for agents)

sync-rpc runs asynchronous commands synchronously by sending them to a separate process over a local port. Prior to 1.3.7, an attacker who could guess that port and reach it (no firewall block) could load and execute arbitrary JavaScript files stored on the server.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed version: `npm ls sync-rpc`
- Check whether `sync-rpc` is a direct or transitive dependency in `package-lock.json` or `yarn.lock`
- Check whether the server's port used by sync-rpc is reachable from outside the host (firewall rules)

## Fix

- `sync-rpc` `1.3.7`

## Timeline

- 2026-11-11T19:28:48+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-65843

## Documents

- [advisory] Vendor advisory: github.com https://github.com/ForbesLindesay/sync-rpc/security/advisories/GHSA-2x86-cf3f-86gw
- [fix] Patch: github.com https://github.com/ForbesLindesay/sync-rpc/commit/ffccfe5bc39ad2e291a79c9e5afe6155ad311f07

## From the sources

sync-rpc runs asynchronous commands synchronously by putting them in a separate proces. Prior to version 1.3.7, if an attacker could guess the correct port and it was not blocked via a firewall, it was possible to load and execute arbitrary JavaScript files stored on the server running sync-rpc. This issue has been patched in version 1.3.7.

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