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Fencer Vulns
high 8.8

CVE-2026-66808 json

Microsoft SharePoint Server Remote Code Execution Vulnerability

published 2026-08-11 2 mo ago modified 2026-10-30 9 d ago also EUVD-2026-56750

cvss
8.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
2.0%
EPSS 2.0% chance of exploitation in 30 days, percentile 81%
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

  • Microsoft Microsoft SharePoint Enterprise Server 2016 16.0.5565.1001
  • Microsoft Microsoft SharePoint Server 2019 16.0.10417.20198
  • Microsoft Microsoft SharePoint Server Subscription Edition 16.0.19725.20522

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-66808 updated cvss 8.7

hypershift-addon-operator: Unsanitized hub ConfigMap data passed as CLI arguments to privileged install Job (Argument Injection)

  • Red Hat multicluster engine for Kubernetes 2.6 multicluster-engine/hypershift-addon-rhel9-operator 1787264068
    fixed: vendor fix RHSA-2026:59579
  • Red Hat multicluster engine for Kubernetes 2.8 multicluster-engine/hypershift-addon-rhel9-operator 1787259113
    fixed: vendor fix RHSA-2026:59558
  • Red Hat multicluster engine for Kubernetes 2.9 multicluster-engine/hypershift-addon-rhel9-operator 1786475964
    fixed: vendor fix RHSA-2026:59559
  • Red Hat multicluster engine for Kubernetes 2.10 multicluster-engine/hypershift-addon-rhel9-operator 1786548381
    fixed: vendor fix RHSA-2026:54432
  • Red Hat multicluster engine for Kubernetes 2.11 multicluster-engine/hypershift-addon-rhel9-operator 1786912006
    fixed: vendor fix RHSA-2026:57194
  • Red Hat multicluster engine for Kubernetes 2.17 multicluster-engine/hypershift-addon-rhel9-operator 1786637185
    fixed: vendor fix RHSA-2026:59593
  • Red Hat multicluster engine for Kubernetes 2.6 multicluster-engine/hive-rhel9 1787291123, multicluster-engine/work-rhel9 1787263188, multicluster-engine/discovery-rhel9 1787263531, multicluster-engine/placement-rhel9 1787260699, multicluster-engine/console-mce-rhel9 1787264250, multicluster-engine/must-gather-rhel9 1787264198, +20 more Red Hat multicluster engine for Kubernetes 2.8 multicluster-engine/hive-rhel9 1787291250, multicluster-engine/work-rhel9 1787259113, multicluster-engine/discovery-rhel9 1787259074, multicluster-engine/placement-rhel9 1787259108, multicluster-engine/console-mce-rhel9 1787259048, multicluster-engine/must-gather-rhel9 1787258992, +20 more Red Hat multicluster engine for Kubernetes 2.9 multicluster-engine/hive-rhel9 1787205132, multicluster-engine/work-rhel9 1786933545, multicluster-engine/discovery-rhel9 1786658519, multicluster-engine/placement-rhel9 1786491555, multicluster-engine/console-mce-rhel9 1787079359, multicluster-engine/must-gather-rhel9 1786837240, +23 more Red Hat multicluster engine for Kubernetes 2.10 multicluster-engine/hive-rhel9 1786549045, multicluster-engine/work-rhel9 1786548903, multicluster-engine/discovery-rhel9 1786549437, multicluster-engine/placement-rhel9 1786548467, multicluster-engine/console-mce-rhel9 1786548913, multicluster-engine/must-gather-rhel9 1786548899, +24 more Red Hat multicluster engine for Kubernetes 2.11 multicluster-engine/hive-rhel9 1786947450, multicluster-engine/work-rhel9 1786907276, multicluster-engine/discovery-rhel9 1786911975, multicluster-engine/placement-rhel9 1786911984, multicluster-engine/console-mce-rhel9 1786911977, multicluster-engine/must-gather-rhel9 1786911926, +25 more Red Hat multicluster engine for Kubernetes 2.17 multicluster-engine/hive-rhel9 1787033495, multicluster-engine/work-rhel9 1786933423, multicluster-engine/maestro-rhel9 1786985023, multicluster-engine/discovery-rhel9 1786681989, multicluster-engine/placement-rhel9 1786983381, multicluster-engine/console-mce-rhel9 1786668856, +28 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
3 mo ago

Exploit prediction

2.04% chance of exploitation in the next 30 days, higher than 81% 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.