Vulnerability-Lookup

GHSA-Q42X-32F8-M4R5

Vulnerability from github – Published: 2026-09-04 12:31 – Updated: 2026-09-04 12:31

Details

Traefik before v2.11.55 contains 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.

Severity

8.2 (High)


                  
                    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

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  "affected": [],
  "aliases": [
    "CVE-2026-85597"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-863"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-04T12:17:23Z",
    "severity": "HIGH"
  },
  "details": "Traefik before v2.11.55 contains 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.",
  "id": "GHSA-q42x-32f8-m4r5",
  "modified": "2026-09-04T12:31:00Z",
  "published": "2026-09-04T12:31:00Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/traefik/traefik/security/advisories/GHSA-g55h-rg46-x9c5"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-85597"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/traefik-before-2.11.55-mtls-bypass-via-tls-option-conflict"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ]
}

CVE-2026-85597 (GCVE-0-2026-85597)

Vulnerability from cvelistv5 – Published: 2026-09-04 11:30 – Updated: 2026-09-04 18:04

Title

Traefik before v2.11.55 mTLS Bypass via TLS Option Conflict

Summary

Severity

8.2 (High)


                        
                          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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-04 18:03 UTC

CWE

CWE-863 - Incorrect Authorization

Assigner

VulnCheck mitre root

References

2 references

URL	Tags
https://github.com/traefik/traefik/security/advis…	vendor-advisory
https://www.vulncheck.com/advisories/traefik-befo…	third-party-advisory

Impacted products

2 products

Vendor	Product	Version
traefik	traefik	Affected: 0 , < 2.11.55 (semver) Unaffected: 2.11.55 (semver)
traefik	traefik	Affected: 3.0.0 , ≤ 3.7.12 (semver)

Date Public

2026-08-21 00:00

Credits

james-yusuke

Show details on NVD website

JSON

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                "id": "CVE-2026-85597",
                "options": [
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                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-09-04T18:03:53.030722Z",
                "version": "2.0.3"
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        "providerMetadata": {
          "dateUpdated": "2026-09-04T18:04:02.286Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

Action not permitted

GHSA-Q42X-32F8-M4R5

CVE-2026-85597 (GCVE-0-2026-85597)

Tags

Sightings

Nomenclature