CVE-2026-85597

Traefik before v2.11.55 and v3.0.0 through v3.7.10 contain a TLS option conflict resolution vulnerability that allows unauthenticated attackers to bypass client-certificate authentication by creating conflicting TLS options on multi-host routers. Attackers can reach protected backends by exploiting shared TLS resolution across multiple hostnames in a single router rule, causing the strict mTLS requirement to fall back to default options for all hosts.

CVSS v3 9.1 CRITICAL

9.1^/10

CVSS v3 : CRITICAL

Vector :

Exploitability : 3.9 / Impact : 5.2

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/traefik/traefik/security/advisories/GHSA-g55h-rg46-x9c5	Exploit Mitigation Patch Vendor Advisory
https://www.vulncheck.com/advisories/traefik-before-2.11.55-mtls-bypass-via-tls-option-conflict	Third Party Advisory

Configurations

Configuration 1 (hide)

OR	cpe:2.3:a:traefik:traefik::::::::
	cpe:2.3:a:traefik:traefik::::::::

History

16 Sep 2026, 20:42

Type	Values Removed	Values Added
CPE		cpe:2.3:a:traefik:traefik::::::::
First Time		Traefik Traefik traefik
CVSS	v2 : ~~unknown~~ v3 : ~~unknown~~	v2 : unknown v3 : 9.1
References	~~() https://github.com/traefik/traefik/security/advisories/GHSA-g55h-rg46-x9c5 -~~	() https://github.com/traefik/traefik/security/advisories/GHSA-g55h-rg46-x9c5 - Exploit, Mitigation, Patch, Vendor Advisory
References	~~() https://www.vulncheck.com/advisories/traefik-before-2.11.55-mtls-bypass-via-tls-option-conflict -~~	() https://www.vulncheck.com/advisories/traefik-before-2.11.55-mtls-bypass-via-tls-option-conflict - Third Party Advisory

Information

Published : 2026-09-04 12:17

Updated : 2026-09-16 20:42

NVD link : CVE-2026-85597

Mitre link : CVE-2026-85597

CVE.ORG link : CVE-2026-85597

JSON object : View

Products Affected

traefik

traefik

CWE

CWE-863

Incorrect Authorization

{"id": "CVE-2026-85597", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-85597", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-09-04T18:03:53.030722Z"}}], "cvssMetricV31": [{"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 9.1, "attackVector": "NETWORK", "baseSeverity": "CRITICAL", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}, "impactScore": 5.2, "exploitabilityScore": 3.9}], "cvssMetricV40": [{"type": "Secondary", "source": "disclosure@vulncheck.com", "cvssData": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "NOT_DEFINED", "baseScore": 8.2, "Automatable": "NOT_DEFINED", "attackVector": "NETWORK", "baseSeverity": "HIGH", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/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", "exploitMaturity": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "userInteraction": "NONE", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "subIntegrityImpact": "NONE", "vulnIntegrityImpact": "NONE", "integrityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "vulnAvailabilityImpact": "NONE", "availabilityRequirement": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "subConfidentialityImpact": "NONE", "vulnConfidentialityImpact": "HIGH", "confidentialityRequirement": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED"}}]}, "affected": [{"source": "disclosure@vulncheck.com", "affectedData": [{"vendor": "traefik", "product": "traefik", "versions": [{"status": "affected", "version": "0", "lessThan": "2.11.55", "versionType": "semver"}, {"status": "unaffected", "version": "2.11.55", "versionType": "semver"}], "packageURL": "pkg:golang/Traefik", "defaultStatus": "unaffected"}, {"vendor": "traefik", "product": "traefik", "versions": [{"status": "affected", "version": "3.0.0", "versionType": "semver", "lessThanOrEqual": "3.7.10"}], "packageURL": "pkg:golang/Traefik", "defaultStatus": "unaffected"}]}], "published": "2026-09-04T12:17:23.210", "references": [{"url": "https://github.com/traefik/traefik/security/advisories/GHSA-g55h-rg46-x9c5", "tags": ["Exploit", "Mitigation", "Patch", "Vendor Advisory"], "source": "disclosure@vulncheck.com"}, {"url": "https://www.vulncheck.com/advisories/traefik-before-2.11.55-mtls-bypass-via-tls-option-conflict", "tags": ["Third Party Advisory"], "source": "disclosure@vulncheck.com"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Secondary", "source": "disclosure@vulncheck.com", "description": [{"lang": "en", "value": "CWE-863"}]}], "descriptions": [{"lang": "en", "value": "Traefik before v2.11.55 and v3.0.0 through v3.7.10 contain a TLS option conflict resolution vulnerability that allows unauthenticated attackers to bypass client-certificate authentication by creating conflicting TLS options on multi-host routers. Attackers can reach protected backends by exploiting shared TLS resolution across multiple hostnames in a single router rule, causing the strict mTLS requirement to fall back to default options for all hosts."}], "lastModified": "2026-09-16T20:42:21.680", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "5322E1E1-46C7-443C-BD3C-5196194D8A90", "versionEndExcluding": "2.11.55"}, {"criteria": "cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "F15D5766-74A9-47EA-AB54-7937D39B17BC", "versionEndExcluding": "3.7.11", "versionStartIncluding": "3.0.0"}], "operator": "OR"}]}], "sourceIdentifier": "disclosure@vulncheck.com"}