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CVE-2026-15937 (GCVE-0-2026-15937)

Vulnerability from cvelistv5 – Published: 2026-09-04 08:24 – Updated: 2026-09-04 08:24
VLAI
Title
Agent receiver certificate confusion allows authentication with a certificate issued for another endpoint
Summary
Improper certificate validation in Checkmk <2.5.0p10 allows a relay and a push agent that share the same UUID to reuse each other's mTLS certificate to authenticate against agent receiver endpoints in either direction, because the endpoints do not verify that the certificate was issued by their own root certificate.
Severity
5.3 (Medium)
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
CWE
  • CWE-295 - Improper Certificate Validation
Assigner
References
URL Tags
https://checkmk.com/werk/19735 vendor-advisory
Impacted products
Vendor Product Version CPE status
Checkmk GmbH Checkmk Affected: 2.5.0 , < 2.5.0p10 (semver)
    cpe:2.3:a:checkmk:checkmk:*:*:*:*:*:*:*:*
Create a notification for this product.
Credits
PS Positive Security GmbH
Show details on NVD website
To clipboard 

{
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          "product": "Checkmk",
          "vendor": "Checkmk GmbH",
          "versions": [
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              "status": "affected",
              "version": "2.5.0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
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                  "versionEndExcluding": "2.5.0p10",
                  "versionStartIncluding": "2.5.0",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "credits": [
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          "type": "reporter",
          "value": "PS Positive Security GmbH"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Improper certificate validation in Checkmk \u003c2.5.0p10 allows a relay and a push agent that share the same UUID to reuse each other\u0027s mTLS certificate to authenticate against agent receiver endpoints in either direction, because the endpoints do not verify that the certificate was issued by their own root certificate."
        }
      ],
      "impacts": [
        {
          "capecId": "CAPEC-114",
          "descriptions": [
            {
              "lang": "en",
              "value": "CAPEC-114: Authentication Abuse"
            }
          ]
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "baseScore": 5.3,
            "baseSeverity": "MEDIUM",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N",
            "version": "4.0"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-295",
              "description": "CWE-295: Improper Certificate Validation",
              "lang": "en",
              "type": "CWE"
            }
          ]
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      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-04T08:24:49.802Z",
        "orgId": "f7d6281c-4801-44ce-ace2-493291dedb0f",
        "shortName": "Checkmk"
      },
      "references": [
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          "tags": [
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          ],
          "url": "https://checkmk.com/werk/19735"
        }
      ],
      "title": "Agent receiver certificate confusion allows authentication with a certificate issued for another endpoint"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "f7d6281c-4801-44ce-ace2-493291dedb0f",
    "assignerShortName": "Checkmk",
    "cveId": "CVE-2026-15937",
    "datePublished": "2026-09-04T08:24:49.802Z",
    "dateReserved": "2026-07-16T08:40:57.255Z",
    "dateUpdated": "2026-09-04T08:24:49.802Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-15937\",\"sourceIdentifier\":\"security@checkmk.com\",\"published\":\"2026-09-04T09:17:10.410\",\"lastModified\":\"2026-09-04T09:17:10.410\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"Improper certificate validation in Checkmk \u003c2.5.0p10 allows a relay and a push agent that share the same UUID to reuse each other\u0027s mTLS certificate to authenticate against agent receiver endpoints in either direction, because the endpoints do not verify that the certificate was issued by their own root certificate.\"}],\"affected\":[{\"source\":\"security@checkmk.com\",\"affectedData\":[{\"vendor\":\"Checkmk GmbH\",\"product\":\"Checkmk\",\"defaultStatus\":\"unaffected\",\"versions\":[{\"version\":\"2.5.0\",\"lessThan\":\"2.5.0p10\",\"versionType\":\"semver\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV40\":[{\"source\":\"security@checkmk.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"4.0\",\"vectorString\":\"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/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\",\"baseScore\":5.3,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"attackRequirements\":\"NONE\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"vulnConfidentialityImpact\":\"LOW\",\"vulnIntegrityImpact\":\"LOW\",\"vulnAvailabilityImpact\":\"NONE\",\"subConfidentialityImpact\":\"NONE\",\"subIntegrityImpact\":\"NONE\",\"subAvailabilityImpact\":\"NONE\",\"exploitMaturity\":\"NOT_DEFINED\",\"confidentialityRequirement\":\"NOT_DEFINED\",\"integrityRequirement\":\"NOT_DEFINED\",\"availabilityRequirement\":\"NOT_DEFINED\",\"modifiedAttackVector\":\"NOT_DEFINED\",\"modifiedAttackComplexity\":\"NOT_DEFINED\",\"modifiedAttackRequirements\":\"NOT_DEFINED\",\"modifiedPrivilegesRequired\":\"NOT_DEFINED\",\"modifiedUserInteraction\":\"NOT_DEFINED\",\"modifiedVulnConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedVulnIntegrityImpact\":\"NOT_DEFINED\",\"modifiedVulnAvailabilityImpact\":\"NOT_DEFINED\",\"modifiedSubConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedSubIntegrityImpact\":\"NOT_DEFINED\",\"modifiedSubAvailabilityImpact\":\"NOT_DEFINED\",\"Safety\":\"NOT_DEFINED\",\"Automatable\":\"NOT_DEFINED\",\"Recovery\":\"NOT_DEFINED\",\"valueDensity\":\"NOT_DEFINED\",\"vulnerabilityResponseEffort\":\"NOT_DEFINED\",\"providerUrgency\":\"NOT_DEFINED\"}}]},\"weaknesses\":[{\"source\":\"security@checkmk.com\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-295\"}]}],\"references\":[{\"url\":\"https://checkmk.com/werk/19735\",\"source\":\"security@checkmk.com\"}]}}"
  }
}



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