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.
History

Wed, 03 Jun 2026 02:30:00 +0000

Type Values Removed Values Added
Description 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.
Title BrowserStack Runner 0.9.5 Unauthenticated RCE via /_log HTTP Handler
Weaknesses CWE-94
References
Metrics cvssV3_1

{'score': 8.8, 'vector': 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}

cvssV4_0

{'score': 8.7, 'vector': 'CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-06-02T20:31:16.903Z

Reserved: 2026-05-27T17:40:12.739Z

Link: CVE-2026-49143

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-06-02T21:16:28.070

Modified: 2026-06-02T21:16:28.070

Link: CVE-2026-49143

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-06-03T04:30:05Z