Use of client-side authentication in Skype for Business allows an authorized attacker to perform spoofing over a network.

cve CVE-2026-66305 1 source, 1 claim · Watch

NVD writes:
Use of client-side authentication in Skype for Business allows an authorized attacker to perform spoofing over a network. the claim

What it is to other things

affectsmicrosoft/skype_for_business_server
NVD
affectsmicrosoft/skype_for_business_server_subscription_edition
NVD
made_bymicrosoft
NVD

In words only, so not counted until a person confirms one:

affectsmicrosoft/skype_for_business_server_2015_cu13
NVD says “Microsoft · Skype for Business Server 2015 CU13”

What each source says

PropertySourceSaidMeans here
Cvss
cvss
NVD7.1
receipt
Source
NVD
Its words
7.1
Read by
field:cve.metrics.cvssMetricV31[].cvssData.baseScore
Said since
2026-09-29 09:45 UTC
Last answered
2026-10-04 12:15 UTC
Original
open at the source
What the source handed over
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      {
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            ]
          },
          {
            "platforms": [
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            ],
            "product": "Skype for Business Server 2019 CU8",
            "vendor": "Microsoft",
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  }
}
—
Product
product
NVDSkype for Business Server 2015 CU13
receipt
Source
NVD
Its words
Skype for Business Server 2015 CU13
Read by
field:cve.affected[].affectedData[].product
Said since
2026-09-29 17:49 UTC
Last answered
2026-10-04 12:15 UTC
Original
open at the source
2026-09-29 17:49 UTCSkype for Business Server 2015 CU13
2026-09-29 09:45 UTC—
What the source handed over
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      {
        "affectedData": [
          {
            "platforms": [
              "x64-based Systems"
            ],
            "product": "Skype for Business Server 2015 CU13",
            "vendor": "Microsoft",
            "versions": [
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                "status": "affected",
                "version": "9319.0",
                "versionType": "custom"
              }
            ]
          },
          {
            "platforms": [
              "x64-based Systems"
            ],
            "product": "Skype for Business Server 2019 CU8",
            "vendor": "Microsoft",
            "versions": [
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                "status": "affected",
                "version": "2046.0",
                "versionType": "custom"
              }
            ]
          },
          {
            "platforms": [
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            ],
            "product": "Skype for Business Server Subscription Edition CU1",
            "vendor": "Microsoft",
            "versions": [
              {
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                "status": "affected",
                "version": "2046.0",
                "versionType": "custom"
              }
            ]
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        ],
        "source": "secure@microsoft.com"
      }
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}
—
Status
status
NVDAnalyzed
receipt
Source
NVD
Its words
Analyzed
Read by
field:cve.vulnStatus
Said since
2026-09-29 09:45 UTC
Last answered
2026-10-04 12:15 UTC
Original
open at the source
What the source handed over
{
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    "affected": [
      {
        "affectedData": [
          {
            "platforms": [
              "x64-based Systems"
            ],
            "product": "Skype for Business Server 2015 CU13",
            "vendor": "Microsoft",
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              }
            ]
          },
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            ],
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                "versionType": "custom"
              }
            ]
          },
          {
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            "product": "Skype for Business Server Subscription Edition CU1",
            "vendor": "Microsoft",
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}
—
Vendor
vendor
NVDMicrosoft
receipt
Source
NVD
Its words
Microsoft
Read by
field:cve.affected[].affectedData[].vendor
Said since
2026-09-29 17:49 UTC
Last answered
2026-10-04 12:15 UTC
Original
open at the source
2026-09-29 17:49 UTCMicrosoft
2026-09-29 09:45 UTC—
What the source handed over
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      {
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          {
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              "x64-based Systems"
            ],
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            "integrityImpact": "HIGH",
            "privilegesRequired": "LOW",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N",
            "version": "3.1"
          },
          "exploitabilityScore": 2.8,
          "impactScore": 4.2,
          "source": "secure@microsoft.com",
          "type": "Secondary"
        }
      ],
      "ssvcV203": [
        {
          "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "ssvcData": {
            "id": "CVE-2026-66305",
            "options": [
              {
                "exploitation": "none"
              },
              {
                "automatable": "no"
              },
              {
                "technicalImpact": "partial"
              }
            ],
            "role": "CISA Coordinator",
            "timestamp": "2026-09-09T15:49:58.190621Z",
            "version": "2.0.3"
          }
        }
      ]
    },
    "published": "2026-09-08T19:18:08.073",
    "references": [
      {
        "source": "secure@microsoft.com",
        "tags": [
          "Patch",
          "Vendor Advisory"
        ],
        "url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66305"
      }
    ],
    "sourceIdentifier": "secure@microsoft.com",
    "vulnStatus": "Analyzed",
    "weaknesses": [
      {
        "description": [
          {
            "lang": "en",
            "value": "CWE-603"
          }
        ],
        "source": "secure@microsoft.com",
        "type": "Secondary"
      }
    ]
  }
}
—

vulnerability

Use of client-side authentication in Skype for Business allows an authorized attacker to perform spoofing over a network.
zetlyn/cve-nvd · 2026-09-08
cvss 7.1 product Skype for Business Server 2015 CU13 status Analyzed vendor Microsoft source