{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-16434", "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "state": "PUBLISHED", "assignerShortName": "VulnCheck", "dateReserved": "2026-07-21T01:28:32.813Z", "datePublished": "2026-08-25T01:29:57.018Z", "dateUpdated": "2026-08-25T01:29:57.018Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "shortName": "VulnCheck", "dateUpdated": "2026-08-25T01:29:57.018Z"}, "datePublic": "2026-07-21T00:00:00.000Z", "title": "Adminer before 5.5.1 X-Forwarded-Prefix Backslash Bypass", "descriptions": [{"lang": "en", "value": "Adminer 4.6.0 through 5.5.0 (fixed in 5.5.1) contains an incomplete fix for a prior X-Forwarded-Prefix vulnerability (GHSA-8478-xrj3-h9c2). The validation guard (bootstrap.inc.php) only rejects prefixes matching ^/[^/], blocking //evil.com but allowing values such as /\\evil.com whose second character is a backslash. Because browsers normalize backslash to forward slash, a network-path reference survives into REQUEST_URI and reaches cookie_path(), affecting the Set-Cookie Path attribute. Exploitation requires that clients can set the X-Forwarded-Prefix header (a misconfigured or absent reverse proxy). Impact is limited to anomalous cookie-path scoping."}], "problemTypes": [{"descriptions": [{"lang": "en", "description": "Improper Input Validation", "cweId": "CWE-20", "type": "CWE"}]}], "affected": [{"vendor": "vrana", "product": "adminer", "defaultStatus": "unaffected", "versions": [{"version": "0", "status": "affected", "versionType": "semver", "lessThan": "5.5.1"}, {"version": "5.5.1", "status": "unaffected", "versionType": "semver"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:adminer:adminer:*:*:*:*:*:*:*:*", "versionEndExcluding": "5.5.1"}]}]}], "metrics": [{"format": "CVSS", "cvssV4_0": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N", "attackVector": "NETWORK", "attackComplexity": "HIGH", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "PASSIVE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "LOW", "vulnAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "baseScore": 2.3, "baseSeverity": "LOW"}}], "references": [{"url": "https://github.com/vrana/adminer/security/advisories/GHSA-fr74-9mf9-gf44", "tags": ["vendor-advisory"], "name": "GitHub Security Advisory (GHSA-fr74-9mf9-gf44)"}, {"name": "VulnCheck Advisory: Adminer before 5.5.1 X-Forwarded-Prefix Backslash Bypass", "tags": ["third-party-advisory"], "url": "https://www.vulncheck.com/advisories/adminer-before-x-forwarded-prefix-backslash-bypass"}], "credits": [{"lang": "en", "value": "Infinit3i", "type": "reporter"}], "x_generator": {"engine": "vulncheck-endgame"}}}}

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{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "adminer", "vendor": "vrana", "versions": [{"lessThan": "5.5.1", "status": "affected", "version": "0", "versionType": "semver"}, {"status": "unaffected", "version": "5.5.1", "versionType": "semver"}]}], "source": "disclosure@vulncheck.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Adminer 4.6.0 through 5.5.0 (fixed in 5.5.1) contains an incomplete fix for a prior X-Forwarded-Prefix vulnerability (GHSA-8478-xrj3-h9c2). The validation guard (bootstrap.inc.php) only rejects prefixes matching ^/[^/], blocking //evil.com but allowing values such as /\\evil.com whose second character is a backslash. Because browsers normalize backslash to forward slash, a network-path reference survives into REQUEST_URI and reaches cookie_path(), affecting the Set-Cookie Path attribute. Exploitation requires that clients can set the X-Forwarded-Prefix header (a misconfigured or absent reverse proxy). Impact is limited to anomalous cookie-path scoping."}], "id": "CVE-2026-16434", "lastModified": "2026-08-25T02:16:40.110", "metrics": {"cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "HIGH", "attackRequirements": "NONE", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 2.3, "baseSeverity": "LOW", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "privilegesRequired": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "PASSIVE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/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", "vulnAvailabilityImpact": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "LOW", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "disclosure@vulncheck.com", "type": "Secondary"}]}, "published": "2026-08-25T02:16:40.110", "references": [{"source": "disclosure@vulncheck.com", "url": "https://github.com/vrana/adminer/security/advisories/GHSA-fr74-9mf9-gf44"}, {"source": "disclosure@vulncheck.com", "url": "https://www.vulncheck.com/advisories/adminer-before-x-forwarded-prefix-backslash-bypass"}], "sourceIdentifier": "disclosure@vulncheck.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-20"}], "source": "disclosure@vulncheck.com", "type": "Primary"}]}

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