---
id: CVE-2026-49143
title: >-
  BrowserStack Runner through 0.9.5 contains a remote code execution
  vulnerability in the /_log HTTP handler that allows unauthenticated
  network-adjacent attackers to execute arbitrary code by submitting crafted
  JSON request bodies to the …
summary: >-
  BrowserStack Runner through 0.9.5 contains a remote code execution
  vulnerability in the /_log HTTP handler that allows unauthenticated
  network-adjacent attackers to execute arbitrary code by submitting crafted
  JSON request bodies to the …
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-94
vendor: browserstack
product: browserstack-runner
affected:
  - browserstack-runner <= 0.9.5
published: '2026-06-02'
updated: '2026-10-08'
sourceUpdated: '2026-10-08T16:17:18.667'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-49143'
references:
  - url: >-
      https://github.com/browserstack/browserstack-runner/security/advisories/GHSA-6vr3-7wcx-v5g5
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/browserstack-runner-unauthenticated-rce-via-log-http-handler
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/browserstack/browserstack-runner/security/advisories/GHSA-6vr3-7wcx-v5g5
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
  - cve.org
  - exploit-available
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-06-03T14:02:08.658694Z'
epss: 0.00671
epssPercentile: 0.50492
ingestedAt: '2026-10-08T16:52:14.685Z'
---

## Overview

BrowserStack Runner through 0.9.5 contains a remote code execution vulnerability in the /_log HTTP handler that allows unauthenticated network-adjacent attackers to execute arbitrary code by submitting crafted JSON request bodies to the handler, which passes user-supplied data to vm.runInNewContext() combined with eval(). Attackers can escape the Node.js vm sandbox by leveraging a host-context Function reference through util.format to access the host process via this.constructor.constructor, achieving full remote code execution on the underlying system without any authentication.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.