CVE-2026-45659 (GCVE-0-2026-45659)

Vulnerability from cvelistv5 – Published: 2026-05-22 22:04 – Updated: 2026-07-02 03:55
VLAI CISA KEVIntel
Title
Microsoft SharePoint Remote Code Execution Vulnerability
Summary
Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.
Severity
8.8 (High)
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
SSVC
Exploitation: active Automatable: no Technical Impact: total
CISA Coordinator (v2.0.3)
CWE
  • CWE-502 - Deserialization of Untrusted Data
Assigner
References
Impacted products
Date Public
2026-05-21 14:00
CISA
Known Exploited Vulnerability - GCVE BCP-07 Compliant
KEV entry ID: 6d365beb-def1-4dbf-9d0b-ca170afddd66

Vulnerability ID: CVE-2026-45659

Status: Confirmed

Status Updated: 2026-07-01 00:00 UTC

Exploited: Yes

Timestamps
First Seen: 2026-07-01
Asserted: 2026-07-01
Scope
Notes: KEV entry: Microsoft SharePoint Server Deserialization of Untrusted Data Vulnerability | Affected: Microsoft / SharePoint Server | Description: Microsoft SharePoint Server contains a deserialization of untrusted data vulnerability which allows an authorized attacker to execute code over a network. | 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. | Due date: 2026-07-04 | Known ransomware campaign use (KEV): Unknown | Notes (KEV): 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
Evidence

Type: Vendor Report

Signal: Successful Exploitation

Confidence: 80%

Source: cisa-kev

Details
Cwes CWE-502
Feed CISA Known Exploited Vulnerabilities Catalog
Product SharePoint Server
Due Date 2026-07-04
Date Added 2026-07-01
Vendorproject Microsoft
Vulnerabilityname Microsoft SharePoint Server Deserialization of Untrusted Data Vulnerability
Knownransomwarecampaignuse Unknown
References
Created: 2026-07-01 20:00 UTC | Updated: 2026-07-01 20:00 UTC
KEVIntel
Known Exploited Vulnerability - GCVE BCP-07 Compliant
KEV entry ID: 657482b4-fc37-4bd2-aded-f92d21f1793a

Vulnerability ID: CVE-2026-45659

Status: Confirmed

Status Updated: 2026-07-01 19:00 UTC

Exploited: Yes

Timestamps
First Seen: 2026-07-01
Asserted: 2026-07-01
Scope
Notes: KEVIntel entry: Microsoft SharePoint Remote Code Execution Vulnerability | Affected: Microsoft / Microsoft SharePoint Enterprise Server 2016, Microsoft SharePoint Server 2019, Microsoft SharePoint Server Subscription Edition | CVSS: 8.8 (HIGH) | EPSS: 0.02781 | Used in malware: unknown | Not yet in CISA KEV: False
Evidence

Type: Public Report

Signal: Successful Exploitation

Confidence: 70%

Source: kevintel

Details
Feed KEVIntel (kevintel.com)
Title Microsoft SharePoint Remote Code Execution Vulnerability
Vendor Microsoft
Product Microsoft SharePoint Enterprise Server 2016, Microsoft SharePoint Server 2019, Microsoft SharePoint Server Subscription Edition
Added Date 2026-07-01T19:00:06.901Z
Cvss Score 8.8
Epss Score 0.02781
Cvss Severity HIGH
Epss Percentile 0.8461
Used In Malware unknown
Ahead Of Cisa Kev None
Not Yet In Cisa Kev False
References
Created: 2026-07-01 20:00 UTC | Updated: 2026-07-01 20:00 UTC
Show details on NVD website
To clipboard 

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Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.