CVE-2026-49143

HIGH 8.8

BrowserStack Runner 0.9.5 Unauthenticated RCE via /_log HTTP Handler

CVSS Score

8.8

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-94
Vendor	browserstack
Product	browserstack-runner
Published	Jun 2, 2026
Last Updated	Jun 3, 2026

Stay Ahead of the Next One

Get instant alerts for browserstack browserstack-runner

Be the first to know when new high vulnerabilities affecting browserstack browserstack-runner are published — delivered to Slack, Telegram or Discord.

Get Free Alerts → Free · No credit card · 60 sec setup

CVSS v3 Breakdown

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector

Adjacent

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Affected Versions

browserstack / browserstack-runner

0 ≤ 0.9.5

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/browserstack/browserstack-runner/security/advisories/GHSA-6vr3-7wcx-v5g5 vulncheck.com: https://www.vulncheck.com/advisories/browserstack-runner-unauthenticated-rce-via-log-http-handler

Credits

Christ Bouchuen