{"id":"EUVD-2026-77579","revision":null,"records":[{"revision":"8398b97b1cfe4ad7a6db154ca3e8cbcc","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-61534","aliases":[],"title":"Yayson: Prototype pollution in the Store/LegacyStore deserialization","description":"Yayson is a library for serializing and reading JSON API data in JavaScript. Prior to 4.3.0, Store and LegacyStore use attacker-controlled JSON:API type, id, and relationship names as keys in plain-object lookup tables in src/yayson/store.ts and src/yayson/legacy-store.ts. A document whose type is __proto__ causes model-cache writes to modify Object.prototype, with the attacker controlling the polluted property name through id and its value through attributes. The malicious type can also be supplied by an included resource, and LegacyStore is reachable when a configured types mapping resolves to __proto__. Unsafe relationship names including __proto__, constructor, and prototype provide additional document-derived member paths. The resulting process-wide prototype pollution can cause denial of service and logic corruption; authorization bypass or code execution depends on suitable gadgets in the consuming application. This issue is fixed in version 4.3.0.","state":0,"publishedAt":"2026-09-14T15:36:48.918+00:00","modifiedAt":"2026-09-14T19:19:45.499+00:00","affected":[{"ecosystem":"Vendor product","name":"yayson","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"confetti\",\n                    \"product\": \"yayson\",\n                    \"versions\": [\n                        {\n                            \"version\": \"< 4.3.0\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H","score":9.1,"severity":"CRITICAL"}],"references":["https://github.com/confetti/yayson/security/advisories/GHSA-325j-mg25-8q58","https://github.com/confetti/yayson/pull/111","https://github.com/confetti/yayson/commit/e460162d5a3ebac86424bead7424957c36f8dff9","https://github.com/confetti/yayson/releases/tag/v4.3.0"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-61534","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-61534","identifiers":["CVE-2026-61534"]},"retained":false,"historicalAffected":[]},{"revision":"d887c0bdf07242648263fcb793a022b0","observedAt":"2026-11-11T15:02:37.514+00:00","statement":{"source":"euvd","id":"EUVD-2026-77579","aliases":["CVE-2026-61534","GHSA-325j-mg25-8q58"],"title":"Yayson is a library for serializing and reading JSON API data in JavaScript. Prior to 4.3.0, Store and LegacyStore use attacker-controlled JSON:API type, id, and relationship names as keys in plain-object lookup tables in src/yayson/store.t…","description":"Yayson is a library for serializing and reading JSON API data in JavaScript. Prior to 4.3.0, Store and LegacyStore use attacker-controlled JSON:API type, id, and relationship names as keys in plain-object lookup tables in src/yayson/store.ts and src/yayson/legacy-store.ts. A document whose type is __proto__ causes model-cache writes to modify Object.prototype, with the attacker controlling the polluted property name through id and its value through attributes. The malicious type can also be supplied by an included resource, and LegacyStore is reachable when a configured types mapping resolves to __proto__. Unsafe relationship names including __proto__, constructor, and prototype provide additional document-derived member paths. The resulting process-wide prototype pollution can cause denial of service and logic corruption; authorization bypass or code execution depends on suitable gadgets in the consuming application. This issue is fixed in version 4.3.0.","state":0,"publishedAt":null,"modifiedAt":null,"affected":[],"metrics":[{"system":"EUVD CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H","score":9.1,"severity":null}],"references":["https://github.com/confetti/yayson/security/advisories/GHSA-325j-mg25-8q58","https://github.com/confetti/yayson/pull/111","https://github.com/confetti/yayson/commit/e460162d5a3ebac86424bead7424957c36f8dff9","https://github.com/confetti/yayson/releases/tag/v4.3.0"],"sourceUrl":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-77579","license":"ENISA EUVD · source terms and attribution apply","enrichment":{"sourceStatus":null,"weaknesses":[],"productCriteria":[],"sourceDates":{"datePublished":"Sep 14, 2026, 3:36:48 PM","dateUpdated":"Sep 14, 2026, 7:19:45 PM"},"relatedAdvisories":[],"note":"EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON."},"key":"euvd:EUVD-2026-77579","identifiers":["EUVD-2026-77579","CVE-2026-61534","GHSA-325j-mg25-8q58"]},"retained":false,"historicalAffected":[]},{"revision":"c392719ab2e943f9b923ad948d6b093a","observedAt":"2026-10-25T14:19:22.811+00:00","statement":{"source":"nvd","id":"CVE-2026-61534","aliases":[],"title":"Yayson is a library for serializing and reading JSON API data in JavaScript. Prior to 4.3.0, Store and LegacyStore use attacker-controlled JSON:API type, id, and relationship names as keys in plain-object lookup tables in src/yayson/store.t…","description":"Yayson is a library for serializing and reading JSON API data in JavaScript. Prior to 4.3.0, Store and LegacyStore use attacker-controlled JSON:API type, id, and relationship names as keys in plain-object lookup tables in src/yayson/store.ts and src/yayson/legacy-store.ts. A document whose type is __proto__ causes model-cache writes to modify Object.prototype, with the attacker controlling the polluted property name through id and its value through attributes. The malicious type can also be supplied by an included resource, and LegacyStore is reachable when a configured types mapping resolves to __proto__. Unsafe relationship names including __proto__, constructor, and prototype provide additional document-derived member paths. The resulting process-wide prototype pollution can cause denial of service and logic corruption; authorization bypass or code execution depends on suitable gadgets in the consuming application. This issue is fixed in version 4.3.0.","state":0,"publishedAt":"2026-09-14T16:17:16.847+00:00","modifiedAt":"2026-09-30T17:51:56.193+00:00","affected":[],"metrics":[{"system":"CVSS 3.1 · security-advisories@github.com · Secondary","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H","score":9.1,"severity":"CRITICAL"}],"references":["https://github.com/confetti/yayson/commit/e460162d5a3ebac86424bead7424957c36f8dff9","https://github.com/confetti/yayson/pull/111","https://github.com/confetti/yayson/releases/tag/v4.3.0","https://github.com/confetti/yayson/security/advisories/GHSA-325j-mg25-8q58"],"sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-61534","license":"NIST NVD usage terms; underlying source attribution retained","enrichment":{"sourceStatus":"Deferred","weaknesses":["CWE-1321"],"productCriteria":[],"sourceDates":{"published":"2026-09-14T16:17:16.847","lastModified":"2026-09-30T17:51:56.193"},"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-2026-61534","identifiers":["CVE-2026-61534"]},"retained":false,"historicalAffected":[]},{"revision":"14dd14cad8ee41b7830ef0cd17a7263d","observedAt":"2026-10-24T13:17:17.793+00:00","statement":{"source":"osv","id":"GHSA-325j-mg25-8q58","aliases":["CVE-2026-61534"],"title":"yayson: Prototype pollution in Store/LegacyStore deserialization","description":"# Summary\n`Store`/`LegacyStore` key internal lookup tables by the `type`, `id`, and relationship names from a JSON:API document. Because these were plain objects, a document with `type: \"__proto__\"` writes onto `Object.prototype`, polluting every object in the process.\n\n# Severity\nSuggested CVSS v3.1 `AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H` (8.1). The guaranteed impact is process-wide DoS / logic corruption; escalation to authorization bypass or RCE is dependent on gadgets in the consuming application.\n\n# Affected / Patched\n- Affected: `<= 4.2.0` (verified in `3.0.0` and `4.2.0`; all 3.x and 4.x).\n- Patched: `4.3.0`.\n\n# Details\n`type` is a string *value*, untouched by `JSON.parse`, and is used directly as an object key:\n```js\nif (!models[type]) models[type] = {}          // models[\"__proto__\"] is Object.prototype → skipped\nif (!models[type][id]) models[type][id] = model // → Object.prototype[id] = model\n```\nThe attacker controls the polluted key (`id`) and value (the model, populated from `attributes`). Pollution persists for the process lifetime. The malicious type can also arrive via an `included` resource referenced by a relationship, bypassing any `data.type` allow-list. `LegacyStore` is additionally reachable when a configured `types` mapping resolves to `\"__proto__\"`.\n\n# Proof of concept\n```js\nconst { Store } = require('yayson')()\nnew Store().sync({ data: { type: '__proto__', id: 'polluted', attributes: { x: 1 } } })\nconsole.log(({}).polluted) // { x: 1, id: 'polluted' }  ← Object.prototype polluted\n```\n\n# Workarounds\nReject documents whose `type` or relationship names are `__proto__`, `constructor`, or `prototype`, or run Node with `--disable-proto=throw`.\n\n# Fix\nNull-prototype lookup tables, rejection of `__proto__`/`constructor`/`prototype` as document-derived member names, `Object.keys()` iteration, and null-prototype normalization of caller-supplied caches.","state":0,"publishedAt":"2026-09-11T22:11:38+00:00","modifiedAt":"2026-09-11T22:15:03.886099+00:00","affected":[{"ecosystem":"npm","name":"yayson","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"},{"kind":"fixed","version":"4.3.0"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V3","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"CRITICAL"}],"references":["https://github.com/confetti/yayson/security/advisories/GHSA-325j-mg25-8q58","https://github.com/confetti/yayson"],"sourceUrl":"https://github.com/advisories/GHSA-325j-mg25-8q58","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-325j-mg25-8q58","identifiers":["GHSA-325j-mg25-8q58","CVE-2026-61534"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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