What’s Vulnerable › Vulnerabilities

CVE-2026-49143: BrowserStack Runner 0.9.5 Unauthenticated RCE via /_log HTTP Handler

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.8% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-02 · updated 2026-10-08
• Weakness: CWE-94

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.

Affected products

• browserstack-runner: through 0.9.5

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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