{"id":"CVE-2026-27837","aliases":["DEBIAN-CVE-2026-27837","EUVD-2026-8788","GHSA-r5mx-6wc6-7h9w","UBUNTU-CVE-2026-27837"],"status":"published","title":"Dottie vulnerable to prototype pollution bypass via non-first path segments in set() and transform()","description":"Dottie provides nested object access and manipulation in JavaScript. Versions 2.0.4 through 2.0.6 contain an incomplete fix for CVE-2023-26132. The prototype pollution guard introduced in commit `7d3aee1` only validates the first segment of a dot-separated path, allowing an attacker to bypass the protection by placing `__proto__` at any position other than the first. Both `dottie.set()` and `dottie.transform()` are affected. Version 2.0.7 contains an updated fix to address the residual vulnerability.","severity":{"version":"3.1","score":6.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00362,"percentile":0.30444,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-1321"],"published":"2026-02-26T00:19:24Z","modified":"2026-10-28T02:30:52Z","fixes":[{"ecosystem":"npm","package":"dottie","fixed_in":["2.0.7"],"sources":["ghsa","osv"]},{"ecosystem":"Debian:14","package":"node-dottie","fixed_in":["2.0.7+~2.0.7-1"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"npm","package":"dottie","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.0.4"},{"last_affected":"2.0.6"},{"fixed":"2.0.7"}]}]},{"source":"osv","ecosystem":"Debian:12","package":"node-dottie","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.0.2-4","2.0.2-4+deb12u1","2.0.6+~2.0.5-1","2.0.6+~2.0.5-2","2.0.7+~2.0.7-1"]},{"source":"osv","ecosystem":"Debian:13","package":"node-dottie","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.0.6+~2.0.5-2","2.0.7+~2.0.7-1"]},{"source":"osv","ecosystem":"Debian:14","package":"node-dottie","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.0.7+~2.0.7-1"}]}],"versions":["2.0.6+~2.0.5-2"]},{"source":"osv","ecosystem":"npm","package":"dottie","ranges":[{"type":"SEMVER","events":[{"introduced":"2.0.4"},{"fixed":"2.0.7"}]}]},{"source":"osv","ecosystem":"Ubuntu:Pro:20.04:LTS","package":"node-dottie","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.0.2-1","2.0.2-1ubuntu0.1~esm1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:22.04:LTS","package":"node-dottie","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.0.2-1","2.0.2-3","2.0.2-4","2.0.2-4ubuntu0.1~esm1"]},{"source":"osv","ecosystem":"Ubuntu:24.04:LTS","package":"node-dottie","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.0.6+~2.0.5-2"]},{"source":"osv","ecosystem":"Ubuntu:25.10","package":"node-dottie","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.0.6+~2.0.5-2"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"node-dottie","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.0.7+~2.0.7-1"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"node-dottie","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.0.6+~2.0.5-2","2.0.7+~2.0.7-1"]}],"products":[{"vendor":"dottie_project","product":"dottie"},{"vendor":"mickhansen","product":"dottie.js"}],"references":[{"url":"https://github.com/mickhansen/dottie.js/security/advisories/GHSA-r5mx-6wc6-7h9w","tags":["x_refsource_CONFIRM","exploit","Exploit","Vendor Advisory","advisory","web","report"]},{"url":"https://github.com/mickhansen/dottie.js/commit/7e8fa1345a4b46325f0eab8d7aeb1c4deaefdb14","tags":["x_refsource_MISC","Patch","fix","web","report"]},{"url":"https://github.com/advisories/GHSA-4gxf-g5gf-22h4","tags":["x_refsource_MISC","Not Applicable","advisory","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-27837","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-r5mx-6wc6-7h9w"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27837.json","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-27837","tags":["advisory"]},{"url":"https://github.com/mickhansen/dottie.js","tags":["package"]},{"url":"https://ubuntu.com/security/CVE-2026-27837","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-27837","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2026-27837","title":"Dottie vulnerable to prototype pollution bypass via non-first path segments in set() and transform()","description":"Dottie provides nested object access and manipulation in JavaScript. Versions 2.0.4 through 2.0.6 contain an incomplete fix for CVE-2023-26132. The prototype pollution guard introduced in commit `7d3aee1` only validates the first segment of a dot-separated path, allowing an attacker to bypass the protection by placing `__proto__` at any position other than the first. Both `dottie.set()` and `dottie.transform()` are affected. Version 2.0.7 contains an updated fix to address the residual vulnerability.","status":"published","published":"2026-02-26T00:19:24.289Z","modified":"2026-02-26T14:40:07.451Z","cvss":[{"version":"3.1","score":6.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L","level":"medium","assessor":"cna"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T14:19:48.461833Z"}],"euvd":[{"id":"EUVD-2026-8788","description":"Dottie provides nested object access and manipulation in JavaScript. Versions 2.0.4 through 2.0.6 contain an incomplete fix for CVE-2023-26132. The prototype pollution guard introduced in commit `7d3aee1` only validates the first segment of a dot-separated path, allowing an attacker to bypass the protection by placing `__proto__` at any position other than the first. Both `dottie.set()` and `dottie.transform()` are affected. Version 2.0.7 contains an updated fix to address the residual vulnerability.","status":"published","published":"2026-02-26T00:19:24Z","modified":"2026-02-26T14:40:07Z","cvss":[{"version":"3.1","score":6.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L","level":"medium"}],"updated_at":"2026-11-02T19:48:28.012266Z"}],"ghsa":[{"id":"GHSA-r5mx-6wc6-7h9w","title":"dottie is vulnerable to Prototype Pollution bypass via non-first path segments in set() and transform()","description":"### Summary\n\ndottie versions 2.0.4 through 2.0.6 contain an incomplete fix for CVE-2023-26132. The prototype pollution guard introduced in commit `7d3aee1` only validates the first segment of a dot-separated path, allowing an attacker to bypass the protection by placing `__proto__` at any position other than the first.\n\nBoth `dottie.set()` and `dottie.transform()` are affected.\n\n### Details\n\nThe existing guard checks only `pieces[0] === '__proto__'`. When a path like `'a.__proto__.polluted'` is used, `pieces[0]` evaluates to `'a'`, not `'__proto__'`, so the guard is bypassed.\n\nInside the traversal loop, `current['__proto__'] = {}` triggers the `__proto__` setter, replacing the intermediate object's prototype. The final value is then written onto this new prototype.\n\n**Important distinction:** This vulnerability does NOT pollute the global `Object.prototype`. It injects properties into a specific object's prototype chain. However, injected properties are invisible to `hasOwnProperty()` and `Object.keys()`, which makes them difficult to detect and can lead to authorization bypass in common coding patterns.\n\n### PoC\n```javascript\nconst dottie = require('dottie');\n\n// set() bypass\nconst obj = {};\ndottie.set(obj, 'session.__proto__.isAdmin', true);\nconsole.log(obj.session.isAdmin);                    // true\nconsole.log(({}).isAdmin);                           // undefined\nconsole.log(obj.session.hasOwnProperty('isAdmin'));  // false\n\n// transform() bypass\nconst flat = { 'user.__proto__.role': 'admin', 'user.name': 'guest' };\nconst result = dottie.transform(flat);\nconsole.log(result.user.role);                       // 'admin'\nconsole.log(({}).role);                              // undefined\n```\n\nTested on Node.js v20 and v22, dottie 2.0.6, Windows 11.\n\n### Impact\n\nThe primary risk is authorization bypass. In a typical server-side scenario where dottie is used to process user input (e.g., via Sequelize, which depends on dottie with ~1.3M weekly npm downloads), an attacker can inject properties like `isAdmin: true` into objects used for access control decisions. Since the injected property is not an own property, standard checks using `hasOwnProperty()` or `Object.keys()` will not reveal it, while property access like `if (session.isAdmin)` will return `true`.\n\nAdditionally, replacing an object's prototype via `current['__proto__'] = {}` strips all inherited methods, potentially causing TypeError exceptions and denial of service.","status":"published","published":"2026-02-26T19:54:34Z","modified":"2026-02-26T19:54:35Z","cvss":[{"version":"3.1","score":6.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L","level":"medium"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T14:39:27.949248Z"}],"nvd":[{"id":"CVE-2026-27837","description":"Dottie provides nested object access and manipulation in JavaScript. Versions 2.0.4 through 2.0.6 contain an incomplete fix for CVE-2023-26132. The prototype pollution guard introduced in commit `7d3aee1` only validates the first segment of a dot-separated path, allowing an attacker to bypass the protection by placing `__proto__` at any position other than the first. Both `dottie.set()` and `dottie.transform()` are affected. Version 2.0.7 contains an updated fix to address the residual vulnerability.","status":"published","published":"2026-02-26T01:16:24.937Z","modified":"2026-06-17T10:27:46.133Z","cvss":[{"version":"3.1","score":6.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L","level":"medium","assessor":"secondary"},{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"primary"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T14:12:07.027269Z"}],"osv":[{"id":"CVE-2026-27837","title":"Dottie vulnerable to prototype pollution bypass via non-first path segments in set() and transform()","description":"Dottie provides nested object access and manipulation in JavaScript. Versions 2.0.4 through 2.0.6 contain an incomplete fix for CVE-2023-26132. The prototype pollution guard introduced in commit `7d3aee1` only validates the first segment of a dot-separated path, allowing an attacker to bypass the protection by placing `__proto__` at any position other than the first. Both `dottie.set()` and `dottie.transform()` are affected. Version 2.0.7 contains an updated fix to address the residual vulnerability.","status":"published","published":"2026-02-26T00:19:24.289Z","modified":"2026-10-28T02:30:52.643527631Z","cvss":[{"version":"3.1","score":6.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L","level":"medium"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T15:45:00.180685Z"},{"id":"DEBIAN-CVE-2026-27837","description":"Dottie provides nested object access and manipulation in JavaScript. Versions 2.0.4 through 2.0.6 contain an incomplete fix for CVE-2023-26132. The prototype pollution guard introduced in commit `7d3aee1` only validates the first segment of a dot-separated path, allowing an attacker to bypass the protection by placing `__proto__` at any position other than the first. Both `dottie.set()` and `dottie.transform()` are affected. Version 2.0.7 contains an updated fix to address the residual vulnerability.","status":"published","published":"2026-02-26T01:16:24.937Z","modified":"2026-10-01T03:03:08.34968841Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"updated_at":"2026-11-02T15:45:53.877573Z"},{"id":"GHSA-r5mx-6wc6-7h9w","title":"dottie is vulnerable to Prototype Pollution bypass via non-first path segments in set() and transform()","description":"### Summary\n\ndottie versions 2.0.4 through 2.0.6 contain an incomplete fix for CVE-2023-26132. The prototype pollution guard introduced in commit `7d3aee1` only validates the first segment of a dot-separated path, allowing an attacker to bypass the protection by placing `__proto__` at any position other than the first.\n\nBoth `dottie.set()` and `dottie.transform()` are affected.\n\n### Details\n\nThe existing guard checks only `pieces[0] === '__proto__'`. When a path like `'a.__proto__.polluted'` is used, `pieces[0]` evaluates to `'a'`, not `'__proto__'`, so the guard is bypassed.\n\nInside the traversal loop, `current['__proto__'] = {}` triggers the `__proto__` setter, replacing the intermediate object's prototype. The final value is then written onto this new prototype.\n\n**Important distinction:** This vulnerability does NOT pollute the global `Object.prototype`. It injects properties into a specific object's prototype chain. However, injected properties are invisible to `hasOwnProperty()` and `Object.keys()`, which makes them difficult to detect and can lead to authorization bypass in common coding patterns.\n\n### PoC\n```javascript\nconst dottie = require('dottie');\n\n// set() bypass\nconst obj = {};\ndottie.set(obj, 'session.__proto__.isAdmin', true);\nconsole.log(obj.session.isAdmin);                    // true\nconsole.log(({}).isAdmin);                           // undefined\nconsole.log(obj.session.hasOwnProperty('isAdmin'));  // false\n\n// transform() bypass\nconst flat = { 'user.__proto__.role': 'admin', 'user.name': 'guest' };\nconst result = dottie.transform(flat);\nconsole.log(result.user.role);                       // 'admin'\nconsole.log(({}).role);                              // undefined\n```\n\nTested on Node.js v20 and v22, dottie 2.0.6, Windows 11.\n\n### Impact\n\nThe primary risk is authorization bypass. In a typical server-side scenario where dottie is used to process user input (e.g., via Sequelize, which depends on dottie with ~1.3M weekly npm downloads), an attacker can inject properties like `isAdmin: true` into objects used for access control decisions. Since the injected property is not an own property, standard checks using `hasOwnProperty()` or `Object.keys()` will not reveal it, while property access like `if (session.isAdmin)` will return `true`.\n\nAdditionally, replacing an object's prototype via `current['__proto__'] = {}` strips all inherited methods, potentially causing TypeError exceptions and denial of service.","status":"published","published":"2026-02-26T19:54:34Z","modified":"2026-02-26T22:11:18.547258Z","cvss":[{"version":"3.1","score":6.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L","level":"medium"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T15:46:55.480549Z"},{"id":"UBUNTU-CVE-2026-27837","description":"Dottie provides nested object access and manipulation in JavaScript. Versions 2.0.4 through 2.0.6 contain an incomplete fix for CVE-2023-26132. The prototype pollution guard introduced in commit `7d3aee1` only validates the first segment of a dot-separated path, allowing an attacker to bypass the protection by placing `__proto__` at any position other than the first. Both `dottie.set()` and `dottie.transform()` are affected. Version 2.0.7 contains an updated fix to address the residual vulnerability.","status":"published","published":"2026-02-26T01:16:00Z","modified":"2026-10-17T12:56:18.005495521Z","cvss":[{"version":"3.1","score":6.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L","level":"medium"},{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"updated_at":"2026-11-02T16:56:08.726452Z"}]}}