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Fencer Vulns
high 8.8

CVE-2026-45659 kev+ ransomware in the critical feed json

Microsoft SharePoint Remote Code Execution Vulnerability

published 2026-05-22 5 mo ago modified 2026-08-11 2 mo ago also EUVD-2026-31518

cvss
8.8
version 3.1, CNA
cisa kev
Exploited
added 2026-07-01, used in ransomware
epss
80.2%
EPSS 80.2% chance of exploitation in 30 days, percentile 99.6%
public exploits
0
none known

Summary

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

Patch / fix

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.

  • Microsoft Microsoft SharePoint Enterprise Server 2016 16.0.5552.1002
  • Microsoft Microsoft SharePoint Server 2019 16.0.10417.20128
  • Microsoft Microsoft SharePoint Server Subscription Edition 16.0.19725.20280

Timeline

  1. Published
  2. CISA SSVC: exploitation active
  3. Added to CISA KEV
  4. CISA patch deadline

Known exploited

Added
4 mo ago
Patch by
2026-07-04 (4 mo ago)
Ransomware
Known to be used in ransomware campaigns
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.
Vendor, product
Microsoft, SharePoint Server
CISA name
Microsoft SharePoint Server Deserialization of Untrusted Data Vulnerability

CISA SSVC

Exploitation
Active, exploited in the wild
Automatable
no
Technical impact
total
Assessed
5 mo ago

Exploit prediction

80.24% chance of exploitation in the next 30 days, higher than 99.6% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 8.8 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
CNA 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

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

Classification

Weakness
  • CWE-502 Deserialization of Untrusted Data

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.