{"id":"CVE-2026-123561","title":"Sveltejs devalue before 5.9.3 __proto__ Rejection Bypass via Property-Key Coercion","summary":"devalue before 5.9.3 allows malformed null-prototype object keys to bypass parse's __proto__ rejection through property-key coercion, an incomplete fix for GHSA-mwv9-gp5h-frr4. Attackers can supply crafted payloads that yield objects wit…","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 < 5.9.3"],"published":"2026-11-08","updated":"2026-11-08","sourceUpdated":"2026-11-08T01:38:01.726Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-123561","references":[{"url":"https://github.com/sveltejs/devalue/security/advisories/GHSA-4q55-j62x-fr9h","label":"GitHub Security Advisory (GHSA-4q55-j62x-fr9h)"},{"url":"https://www.vulncheck.com/advisories/sveltejs-devalue-before-5.9.3-proto-rejection-bypass-via-property-key-coercion","label":"VulnCheck Advisory: Sveltejs devalue before 5.9.3 __proto__ Rejection Bypass via Property-Key Coercion"}],"tags":["cve.org"],"ingestedAt":"2026-11-08T02:43:18.661Z","slug":"CVE-2026-123561","body":"## Overview\n\ndevalue before 5.9.3 allows malformed null-prototype object keys to bypass parse's __proto__ rejection through property-key coercion, an incomplete fix for GHSA-mwv9-gp5h-frr4. Attackers can supply crafted payloads that yield objects with a __proto__ own property, which alone does not cause prototype pollution.\n\n## Affected\n\n- `devalue < 5.9.3`\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":[]}