Vulnerability 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.
CVSS Score
HIGH
Related Weaknesses (CWE)
References
- https://github.com/browserstack/browserstack-runner/security/advisories/GHSA-6vr
- https://www.vulncheck.com/advisories/browserstack-runner-unauthenticated-rce-via
- https://github.com/browserstack/browserstack-runner/security/advisories/GHSA-6vr
FAQ
What is CVE-2026-49143?
CVE-2026-49143 is a vulnerability with a CVSS score of 8.8 (HIGH). 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 submittin...
How severe is CVE-2026-49143?
CVE-2026-49143 has been rated HIGH with a CVSS base score of 8.8/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-49143?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.