{"id":"CVE-2026-123567","title":"Sveltejs devalue before 5.6.4 Prototype Injection via parse and unflatten","summary":"Sveltejs devalue before 5.6.4 contains a prototype injection vulnerability that allows attackers to inject __proto__ own properties into objects returned by devalue.parse and devalue.unflatten. Attackers can supply crafted serialized inp…","severity":"low","cvss":3.7,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","cvssSource":"cna","cwe":["CWE-1321"],"vendor":"sveltejs","product":"devalue","affected":["devalue < 5.6.4"],"published":"2026-11-08","updated":"2026-11-08","sourceUpdated":"2026-11-08T01:38:05.840Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-123567","references":[{"url":"https://github.com/sveltejs/devalue/security/advisories/GHSA-mwv9-gp5h-frr4","label":"GitHub Security Advisory (GHSA-mwv9-gp5h-frr4)"},{"url":"https://www.vulncheck.com/advisories/sveltejs-devalue-before-5.6.4-prototype-injection-via-parse-and-unflatten","label":"VulnCheck Advisory: Sveltejs devalue before 5.6.4 Prototype Injection via parse and unflatten"}],"tags":["cve.org"],"ingestedAt":"2026-11-08T02:43:18.659Z","slug":"CVE-2026-123567","body":"## Overview\n\nSveltejs devalue before 5.6.4 contains a prototype injection vulnerability that allows attackers to inject __proto__ own properties into objects returned by devalue.parse and devalue.unflatten. Attackers can supply crafted serialized input that, when downstream code merges results via Object.assign, alters the target object's prototype.\n\n## Affected\n\n- `devalue < 5.6.4`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":20,"depthScoreParts":{"impact":20.4,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}