CVE-2026-49143 PUBLISHED

BrowserStack Runner 0.9.5 Unauthenticated RCE via /_log HTTP Handler

Assigner: VulnCheck
Reserved: 27.05.2026 Published: 02.06.2026 Updated: 03.06.2026

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.

Metrics

CVSS 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
CVSS Score: 8.7

Product Status

Vendor browserstack
Product browserstack-runner
Versions Default: affected
  • affected from 0 to 0.9.5 (incl.)

Credits

  • Christ Bouchuen finder

References

Problem Types

  • Improper Control of Generation of Code ('Code Injection') CWE