CVE-2026-56191

{"id": "CVE-2026-56191", "cveTags": [{"tags": ["exclusively-hosted-service"], "sourceIdentifier": "secure@microsoft.com"}], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-56191", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "total"}], "version": "2.0.3", "timestamp": "2026-07-24T00:00:00+00:00"}}], "cvssMetricV31": [{"type": "Secondary", "source": "secure@microsoft.com", "cvssData": {"scope": "CHANGED", "version": "3.1", "baseScore": 10.0, "attackVector": "NETWORK", "baseSeverity": "CRITICAL", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}, "impactScore": 6.0, "exploitabilityScore": 3.9}]}, "affected": [{"source": "secure@microsoft.com", "affectedData": [{"vendor": "Microsoft", "product": "Microsoft Exchange Online", "versions": [{"status": "affected", "version": "-"}]}]}], "published": "2026-07-24T01:17:36.417", "references": [{"url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56191", "tags": ["Vendor Advisory"], "source": "secure@microsoft.com"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Secondary", "source": "secure@microsoft.com", "description": [{"lang": "en", "value": "CWE-287"}]}], "descriptions": [{"lang": "en", "value": "Improper authentication in Microsoft Exchange Online allows an unauthorized attacker to perform tampering over a network."}], "lastModified": "2026-07-29T14:55:55.733", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:microsoft:exchange_online:-:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "DA6C3728-2BB2-4BA9-BB20-D784F18AD402"}], "operator": "OR"}]}], "sourceIdentifier": "secure@microsoft.com"}