CVE-2026-56191

{
  "id": "CVE-2026-56191",
  "sourceIdentifier": "[email protected]",
  "published": "2026-07-24T01:17:36.417",
  "lastModified": "2026-10-24T13:10:00.147",
  "vulnStatus": "Analyzed",
  "cveTags": [
    {
      "sourceIdentifier": "[email protected]",
      "tags": [
        "exclusively-hosted-service"
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Improper authentication in Microsoft Exchange Online allows an unauthorized attacker to perform tampering over a network."
    },
    {
      "lang": "es",
      "value": "Autenticación indebida en Microsoft Exchange Online permite a un atacante no autorizado realizar manipulaciones a través de una red."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "Microsoft",
          "product": "Microsoft Exchange Online",
          "versions": [
            {
              "version": "-",
              "status": "affected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "[email protected]",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H",
          "baseScore": 10.0,
          "baseSeverity": "CRITICAL",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "scope": "CHANGED",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "availabilityImpact": "HIGH"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 6.0
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-07-24T00:00:00+00:00",
          "id": "CVE-2026-56191",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "[email protected]",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-287"
        }
      ]
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "operator": "OR",
          "negate": false,
          "cpeMatch": [
            {
              "vulnerable": true,
              "criteria": "cpe:2.3:a:microsoft:exchange_online:-:*:*:*:*:*:*:*",
              "matchCriteriaId": "DA6C3728-2BB2-4BA9-BB20-D784F18AD402"
            }
          ]
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56191",
      "source": "[email protected]",
      "tags": [
        "Vendor Advisory"
      ]
    }
  ]
}