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CVE-2026-45659 · CVE record: PUBLISHED

Microsoft SharePoint Remote Code Execution Vulnerability

Microsoft Microsoft SharePoint Enterprise Server 2016, Microsoft Microsoft SharePoint Server 2019, Microsoft Microsoft SharePoint Server Subscription Edition

Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.

Exploitation evidence

Known exploited · CISA KEV listed

Added 2026-07-01. Ransomware campaign use: Known.

CISA required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

CISA due date: 2026-07-04. This is the catalog’s deadline, not an assessment of your organization’s exposure.

KEV checked 13 Nov 2026, 00:20 Jerusalem · Original catalog ↗

Reported products and versions

Microsoft / Microsoft SharePoint Enterprise Server 2016

Default status: Not specified

affected: 16.0.0 to < 16.0.5552.1002 (custom)

Microsoft / Microsoft SharePoint Server 2019

Default status: Not specified

affected: 16.0.0 to < 16.0.10417.20128 (custom)

Microsoft / Microsoft SharePoint Server Subscription Edition

Default status: Not specified

affected: 16.0.0 to < 16.0.19725.20280 (custom)

Fixes and workarounds

No explicit solution text in the downloaded CVE record. Consult the vendor advisory; unaffected version ranges are shown above as reported, not inferred as a patch recommendation.

Sources and related reporting

CVE Program record ↗ · Download tracked evidence as JSON

Monitored source mentions

Securelist — Desktop and IoT threat statistics for Q3 2026 ↗

Shared CVE identifiers link source mentions; they do not establish that the reports describe the same incident.

Observed change timeline

History begins when Egret first downloads each source. It is not the complete upstream CVE history.

12 Nov 2026, 18:20 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-12",
  "epss": 0.80242,
  "percentile": 0.99624
}

10 Nov 2026, 18:20 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-10",
  "epss": 0.80242,
  "percentile": 0.99622
}

09 Nov 2026, 18:20 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-09",
  "epss": 0.80242,
  "percentile": 0.99621
}

08 Nov 2026, 18:20 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-08",
  "epss": 0.80242,
  "percentile": 0.99621
}

07 Nov 2026, 18:20 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-07",
  "epss": 0.80242,
  "percentile": 0.99621
}

06 Nov 2026, 18:20 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-06",
  "epss": 0.80242,
  "percentile": 0.99621
}

06 Nov 2026, 06:20 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-05",
  "epss": 0.80242,
  "percentile": 0.9962
}

04 Nov 2026, 18:20 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-04",
  "epss": 0.80242,
  "percentile": 0.9962
}

03 Nov 2026, 18:20 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-03",
  "epss": 0.80242,
  "percentile": 0.99619
}

03 Nov 2026, 12:20 Jerusalem · CVE Program record changed

Stored CNA snapshot at this observation.

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-45659",
                "options": [
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                    "Exploitation": "active"
                  },
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                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-05-26T00:00:00+00:00",
                "version": "2.0.3"
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              "type": "ssvc"
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          },
          {
            "other": {
              "content": {
                "dateAdded": "2026-07-01",
                "reference": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-45659"
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        "providerMetadata": {
          "dateUpdated": "2026-08-11T03:55:31.769Z",
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        "references": [
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        ],
        "timeline": [
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            "lang": "en",
            "time": "2026-07-01T00:00:00.000Z",
            "value": "CVE-2026-45659 added to CISA KEV"
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        ],
        "title": "CISA ADP Vulnrichment"
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    ],
    "cna": {
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          "platforms": [
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          ],
          "product": "Microsoft SharePoint Enterprise Server 2016",
          "vendor": "Microsoft",
          "versions": [
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        },
        {
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          "product": "Microsoft SharePoint Server 2019",
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      "cpeApplicability": [
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              "negate": false,
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      "datePublic": "2026-05-21T14:00:00.000Z",
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        }
      ],
      "metrics": [
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          "cvssV3_1": {
            "baseScore": 8.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C",
            "version": "3.1"
          },
          "format": "CVSS",
          "scenarios": [
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          ]
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      ],
      "problemTypes": [
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          "descriptions": [
            {
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              "lang": "en-US",
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      "providerMetadata": {
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      "references": [
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  "cveMetadata": {
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    "datePublished": "2026-05-22T22:04:33.517Z",
    "dateReserved": "2026-05-12T20:33:35.158Z",
    "dateUpdated": "2026-08-11T03:55:31.769Z",
    "state": "PUBLISHED"
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  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

03 Nov 2026, 02:22 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-02",
  "epss": 0.80242,
  "percentile": 0.99619
}

03 Nov 2026, 02:22 Jerusalem · CISA KEV status changed

Stored KEV snapshot at this observation.

{
  "cveID": "CVE-2026-45659",
  "cwes": [
    "CWE-502"
  ],
  "dateAdded": "2026-07-01",
  "dueDate": "2026-07-04",
  "forensicTriage": "Yes",
  "knownRansomwareCampaignUse": "Known",
  "notes": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45659 ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-45659",
  "product": "SharePoint Server",
  "requiredAction": "Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.",
  "shortDescription": "Microsoft SharePoint Server contains a deserialization of untrusted data vulnerability which allows an authorized attacker to execute code over a network.",
  "vendorProject": "Microsoft",
  "vulnerabilityName": "Microsoft SharePoint Server Deserialization of Untrusted Data Vulnerability"
}

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