{"affected":[{"defaultStatus":"unaffected","ecosystem":"npm","packageName":"devalue","product":"devalue","source":"CNA: VulnCheck","vendor":"sveltejs","versions":[{"lessThan":"5.9.3","status":"affected","version":"0","versionType":"semver"},{"status":"unaffected","version":"5.9.3","versionType":"semver"}]},{"defaultStatus":"unaffected","ecosystem":"npm","packageName":"devalue","product":"devalue","source":"OSV GHSA-4q55-j62x-fr9h","vendor":"","versions":[{"events":[{"introduced":"0"},{"fixed":"5.9.3"}],"lessThan":"5.9.3","status":"affected","version":"0","versionType":"semver"}]}],"cveId":"CVE-2026-123561","cwes":["CWE-1321"],"description":"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 with a __proto__ own property, which alone does not cause prototype pollution.","epss":{"date":"2026-11-10","percentile":0.16311,"score":0.00249},"exploits":[],"kev":null,"metrics":[{"score":6.3,"severity":"medium","source":"CNA: VulnCheck","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N","version":"4.0"},{"score":3.7,"severity":"low","source":"CNA: VulnCheck","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","version":"3.1"},{"score":6.3,"severity":"medium","source":"NVD: disclosure@vulncheck.com","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","version":"4.0"},{"score":3.7,"severity":"low","source":"NVD: disclosure@vulncheck.com","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","version":"3.1"}],"modifiedAt":1794333515941,"publishedAt":1794101881726,"references":[{"source":"CNA: VulnCheck","tags":["vendor-advisory"],"url":"https://github.com/sveltejs/devalue/security/advisories/GHSA-4q55-j62x-fr9h"},{"source":"CNA: VulnCheck","tags":["third-party-advisory"],"url":"https://www.vulncheck.com/advisories/sveltejs-devalue-before-5.9.3-proto-rejection-bypass-via-property-key-coercion"},{"source":"disclosure@vulncheck.com","tags":[],"url":"https://github.com/sveltejs/devalue/security/advisories/GHSA-4q55-j62x-fr9h"},{"source":"disclosure@vulncheck.com","tags":[],"url":"https://www.vulncheck.com/advisories/sveltejs-devalue-before-5.9.3-proto-rejection-bypass-via-property-key-coercion"},{"source":"OSV / GitHub Security Advisories","tags":["advisory"],"url":"https://github.com/advisories/GHSA-4q55-j62x-fr9h"},{"source":"OSV / GitHub Security Advisories","tags":["osv"],"url":"https://osv.dev/vulnerability/GHSA-4q55-j62x-fr9h"}],"remediation":[{"kind":"fix","source":"OSV GHSA-4q55-j62x-fr9h","text":"devalue (npm): OSV reports a fixed version 5.9.3. Check the advisory for supported release branches.","url":"https://github.com/advisories/GHSA-4q55-j62x-fr9h"}],"revision":"d1f11d3c9d0f6ed47663a103819f79e33709c232c16ab2868c35d11c4daec37e","sources":[{"modifiedAt":1794333515941,"name":"CNA: VulnCheck","retrievedAt":1794334215357,"url":"https://www.cve.org/CVERecord?id=CVE-2026-123561"},{"modifiedAt":1794104208400,"name":"NVD","retrievedAt":1794118575082,"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-123561"},{"modifiedAt":1794135373484,"name":"OSV / GitHub Security Advisories","retrievedAt":1794334216804,"url":"https://osv.dev/vulnerability/GHSA-4q55-j62x-fr9h"},{"modifiedAt":null,"name":"FIRST EPSS","retrievedAt":1794334234732,"url":"https://api.first.org/data/v1/epss?cve=CVE-2026-123561"}],"ssvc":{"assessedAt":1794325316785,"automatable":"no","exploitation":"none","source":"ADP: CISA-ADP","technicalImpact":"partial"},"status":"published","title":"Sveltejs devalue before 5.9.3 __proto__ Rejection Bypass via Property-Key Coercion","updatedAt":1794334234732}