Microsoft Office SharePoint
CVE-2026-55021 — Microsoft SharePoint Server Spoofing Vulnerability
Executive Summary
Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Office SharePoint allows an authorized attacker to perform spoofing over a network.
Overview
8.7
CVSS HIGH
Important
MS Severity
Not Exploited
MS Exploit Status
Exploitation Unlikely
MS Exploit Likelihood
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N/E:U/RL:O/RC:C
ATTACK VECTOR
Network
ATTACK COMPLEXITY
Low
PRIVILEGES REQUIRED
Low
USER INTERACTION
Required
SCOPE
Changed
CONFIDENTIALITY
High
INTEGRITY
High
AVAILABILITY
None
EXPLOIT CODE MATURITY
Unproven
REMEDIATION LEVEL
Official Fix
REPORT CONFIDENCE
Confirmed
Temporal Score: 6.4
EPSS Score
0.00651
probability of exploitation in the next 30 days
0.48093 percentile - updated 2026-08-14
View on FIRST.org
Affected Products
3 affected products
| Product | KB Article | Severity | Impact | Restart Required |
|---|---|---|---|---|
| Microsoft SharePoint Enterprise Server 2016 | 5002891 (Security Update) |
Important | Spoofing | Maybe |
| Microsoft SharePoint Server 2019 | 5002883 (Security Update) |
Important | Spoofing | Maybe |
| Microsoft SharePoint Server Subscription Edition | 5002882 (Security Update) |
Important | Spoofing | Maybe |
Patches
3 patches
| Article | Type | Restart |
|---|---|---|
5002891 |
Security Update | Maybe |
5002883 |
Security Update | Maybe |
5002882 |
Security Update | Maybe |
Exploits & PoC
No public exploit or PoC has been linked for this CVE yet. When available, references are sourced from public repositories and may be unverified or non-functional — review carefully before use.
Detection Rules
No public Sigma or Nuclei detection rule has been mapped to this CVE yet. Coverage is concentrated on exploited / high-profile vulnerabilities; check SigmaHQ for updates.
Acknowledgments
P1hcn
References
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