{"affected":[{"defaultStatus":"unaffected","ecosystem":"npm","packageName":"devalue","product":"devalue","source":"CNA: VulnCheck","vendor":"sveltejs","versions":[{"lessThan":"5.6.4","status":"affected","version":"0","versionType":"semver"},{"status":"unaffected","version":"5.6.4","versionType":"semver"}]},{"defaultStatus":"unaffected","ecosystem":"npm","packageName":"devalue","product":"devalue","source":"OSV GHSA-mwv9-gp5h-frr4","vendor":"","versions":[{"events":[{"introduced":"4.0.0"},{"fixed":"5.6.4"}],"lessThan":"5.6.4","status":"affected","version":"4.0.0","versionType":"semver"}]}],"cveId":"CVE-2026-123567","cwes":["CWE-1321"],"description":"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 input that, when downstream code merges results via Object.assign, alters the target object's prototype.","epss":{"date":"2026-11-12","percentile":0.14831,"score":0.00237},"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":1794539033496,"publishedAt":1794101885840,"references":[{"source":"CNA: VulnCheck","tags":["vendor-advisory"],"url":"https://github.com/sveltejs/devalue/security/advisories/GHSA-mwv9-gp5h-frr4"},{"source":"CNA: VulnCheck","tags":["third-party-advisory"],"url":"https://www.vulncheck.com/advisories/sveltejs-devalue-before-5.6.4-prototype-injection-via-parse-and-unflatten"},{"source":"disclosure@vulncheck.com","tags":[],"url":"https://github.com/sveltejs/devalue/security/advisories/GHSA-mwv9-gp5h-frr4"},{"source":"disclosure@vulncheck.com","tags":[],"url":"https://www.vulncheck.com/advisories/sveltejs-devalue-before-5.6.4-prototype-injection-via-parse-and-unflatten"},{"source":"OSV / GitHub Security Advisories","tags":["advisory"],"url":"https://github.com/advisories/GHSA-mwv9-gp5h-frr4"},{"source":"OSV / GitHub Security Advisories","tags":["osv"],"url":"https://osv.dev/vulnerability/GHSA-mwv9-gp5h-frr4"}],"remediation":[{"kind":"fix","source":"OSV GHSA-mwv9-gp5h-frr4","text":"devalue (npm): OSV reports a fixed version 5.6.4. Check the advisory for supported release branches.","url":"https://github.com/advisories/GHSA-mwv9-gp5h-frr4"}],"revision":"78f69e0a1fdc19dd9d116c78b9afe724a2db62c462e831cdb1b1f7a9959d03b0","sources":[{"modifiedAt":1794539033496,"name":"CNA: VulnCheck","retrievedAt":1794542910019,"url":"https://www.cve.org/CVERecord?id=CVE-2026-123567"},{"modifiedAt":1794519347960,"name":"NVD","retrievedAt":1794529128646,"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-123567"},{"modifiedAt":1794135374491,"name":"OSV / GitHub Security Advisories","retrievedAt":1794542910464,"url":"https://osv.dev/vulnerability/GHSA-mwv9-gp5h-frr4"},{"modifiedAt":null,"name":"FIRST EPSS","retrievedAt":1794542929475,"url":"https://api.first.org/data/v1/epss?cve=CVE-2026-123567"}],"ssvc":{"assessedAt":1794539023372,"automatable":"no","exploitation":"none","source":"ADP: CISA-ADP","technicalImpact":"partial"},"status":"published","title":"Sveltejs devalue before 5.6.4 Prototype Injection via parse and unflatten","updatedAt":1794542929475}