{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-123567", "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "state": "PUBLISHED", "assignerShortName": "VulnCheck", "dateReserved": "2026-11-06T00:53:14.312Z", "datePublished": "2026-11-08T01:38:05.840Z", "dateUpdated": "2026-11-08T01:38:05.840Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "shortName": "VulnCheck", "dateUpdated": "2026-11-08T01:38:05.840Z"}, "datePublic": "2026-03-11T00:00:00.000Z", "title": "Sveltejs devalue before 5.6.4 Prototype Injection via parse and unflatten", "descriptions": [{"lang": "en", "value": "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."}], "problemTypes": [{"descriptions": [{"lang": "en", "description": "Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')", "cweId": "CWE-1321", "type": "CWE"}]}], "affected": [{"vendor": "sveltejs", "product": "devalue", "defaultStatus": "unaffected", "packageURL": "pkg:npm/devalue", "versions": [{"version": "0", "status": "affected", "versionType": "semver", "lessThan": "5.6.4"}, {"version": "5.6.4", "status": "unaffected", "versionType": "semver"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:svelte:devalue:*:*:*:*:*:*:*:*", "versionEndExcluding": "5.6.4"}]}]}], "metrics": [{"cvssV4_0": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "attackVector": "NETWORK", "baseScore": 6.3, "baseSeverity": "MEDIUM", "exploitMaturity": "NOT_DEFINED", "privilegesRequired": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "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", "vulnAvailabilityImpact": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "LOW", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "format": "CVSS"}, {"cvssV3_1": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 3.7, "baseSeverity": "LOW", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N", "version": "3.1"}, "format": "CVSS"}], "references": [{"url": "https://github.com/sveltejs/devalue/security/advisories/GHSA-mwv9-gp5h-frr4", "tags": ["vendor-advisory"], "name": "GitHub Security Advisory (GHSA-mwv9-gp5h-frr4)"}, {"name": "VulnCheck Advisory: Sveltejs devalue before 5.6.4 Prototype Injection via parse and unflatten", "tags": ["third-party-advisory"], "url": "https://www.vulncheck.com/advisories/sveltejs-devalue-before-5.6.4-prototype-injection-via-parse-and-unflatten"}], "credits": [{"lang": "en", "value": "elliott-with-the-longest-name-on-github", "type": "remediation developer"}, {"lang": "en", "value": "KarimPwnz", "type": "remediation reviewer"}, {"lang": "en", "value": "wim-vercel", "type": "remediation reviewer"}, {"lang": "en", "value": "mattiasljungstrom", "type": "reporter"}], "x_generator": {"engine": "vulncheck-endgame"}}}}