{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-126401", "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "state": "PUBLISHED", "assignerShortName": "VulnCheck", "dateReserved": "2026-11-10T21:32:21.765Z", "datePublished": "2026-11-13T09:35:47.679Z", "dateUpdated": "2026-11-13T09:35:47.679Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "shortName": "VulnCheck", "dateUpdated": "2026-11-13T09:35:47.679Z"}, "datePublic": "2026-10-28T00:00:00.000Z", "title": "Fleet before 4.86.2 Unauthenticated DoS via SSO Callback XML Canonicalization", "descriptions": [{"lang": "en", "value": "Fleet before 4.86.2 contains a denial of service vulnerability that allows unauthenticated attackers to exhaust server memory through quadratic XML canonicalization of unsigned SAML responses. Attackers can send a single crafted SAML response with deeply nested elements declaring new namespace prefixes to POST /api/v1/fleet/sso/callback, crashing the Fleet server."}], "problemTypes": [{"descriptions": [{"lang": "en", "description": "Inefficient Algorithmic Complexity", "cweId": "CWE-407", "type": "CWE"}]}], "affected": [{"vendor": "fleetdm", "product": "fleet", "defaultStatus": "unaffected", "packageURL": "pkg:golang/github.com/fleetdm/fleet", "versions": [{"version": "0", "status": "affected", "versionType": "semver", "lessThan": "4.86.2"}, {"version": "4.86.2", "status": "unaffected", "versionType": "semver"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:fleetdm:fleet:*:*:*:*:*:*:*:*", "versionEndExcluding": "4.86.2"}]}]}], "metrics": [{"cvssV4_0": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "NETWORK", "baseScore": 8.7, "baseSeverity": "HIGH", "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:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N", "version": "4.0", "vulnAvailabilityImpact": "HIGH", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "format": "CVSS"}, {"cvssV3_1": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 7.5, "baseSeverity": "HIGH", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}, "format": "CVSS"}], "references": [{"url": "https://github.com/fleetdm/fleet/security/advisories/GHSA-mjrh-3v6h-8g5p", "tags": ["vendor-advisory"], "name": "GitHub Security Advisory (GHSA-mjrh-3v6h-8g5p)"}, {"name": "VulnCheck Advisory: Fleet before 4.86.2 Unauthenticated DoS via SSO Callback XML Canonicalization", "tags": ["third-party-advisory"], "url": "https://www.vulncheck.com/advisories/fleet-before-4.86.2-unauthenticated-dos-via-sso-callback-xml-canonicalization"}], "credits": [{"lang": "en", "value": "fuzzztf", "type": "reporter"}], "x_generator": {"engine": "vulncheck-endgame"}}}}

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{}