BrowserStack Runner 0.9.5 Unauthenticated RCE via /_log HTTP Handler_CVE-2026-49143

{
    "lastseen": "",
    "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.",
    "published": "2026-06-02T20:31:16.903Z",
    "modified": "2026-06-02T20:31:16.903Z",
    "type": "cve",
    "title": "BrowserStack Runner 0.9.5 Unauthenticated RCE via /_log HTTP Handler",
    "source": "VulnCheck",
    "references": "https://github.com/browserstack/browserstack-runner/security/advisories/GHSA-6vr3-7wcx-v5g5\nhttps://www.vulncheck.com/advisories/browserstack-runner-unauthenticated-rce-via-log-http-handler",
    "id": "CVE-2026-49143",
    "bulletinFamily": "",
    "cwe": [
        "CWE-94"
    ],
    "cvelist": null,
    "sourceData": "browserstack browserstack-runner 0",
    "sourceHref": "",
    "cvss": {
        "score": 8.7,
        "severity": "HIGH",
        "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",
        "version": "4.0"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
            "attackComplexity": "",
            "privilegesRequired": "",
            "userInteraction": "",
            "scope": "",
            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "browserstack-runner",
    "version": "0",
    "vendor": "browserstack",
    "ai_description": "Unauthenticated remote code execution vulnerability in BrowserStack Runner through 0.9.5 via /_log HTTP handler",
    "ai_severity": "High",
    "ai_vendor": "BrowserStack",
    "ai_product": "BrowserStack Runner",
    "ai_version": "0.9.5",
    "ai_score": 8.7
}