CVE-2026-49143

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 4.0

8.7CVSS: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 3.1

8.8CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

0.8% chance of exploitation in the next 30 days; higher than 56% of CVEs (scores of 2026-10-25)

CWE

CWE-94

Published

2026-06-02

Modified

2026-10-08

Record from

the NVD, synced 2026-10-19

Packages (OSV)

References

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

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