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CVE-2021-28478

25
FAUCET Score

CVE-2021-28478 is a spoofing vulnerability affecting Microsoft SharePoint Server and SharePoint Foundation. With a CVSS score of 7.6 (High), it allows an authenticated attacker to achieve high confidentiality and low integrity impact through a network-based attack requiring user interaction. While there is no evidence of active exploitation, public exploit code, or KEV listing, the vulnerability has garnered some community discussion and media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
2013CPE matchmatch criteria
cpe:2.3:a:microsoft:sharepoint_foundation:2013:sp1:*:*:*:*:*:*
2016CPE matchmatch criteria
cpe:2.3:a:microsoft:sharepoint_server:2016:*:*:*:enterprise:*:*:*
2019CPE matchmatch criteria
cpe:2.3:a:microsoft:sharepoint_server:2019:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.6HIGH

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
2.3
Impact Score
4.7
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.52%
Probability of exploitation in next 30 days
EPSS Percentile
72.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0152 is in the 88th percentile among its peer group of 890 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.3 Bluesky, 0.1 Mastodon, and 0.1 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (4)

microsoftpatch availablevia nvd_reference
View patch
microsoftpatch availablevia msrc
Product: Microsoft SharePoint Enterprise Server 2016Fixed in: 16.0.5161.1000
View patch
microsoftpatch availablevia msrc
Product: Microsoft SharePoint Server 2019Fixed in: 16.0.10374.20000
View patch
microsoftpatch availablevia msrc
Product: Microsoft SharePoint Foundation 2013 Service Pack 1Fixed in: 15.0.5345.1000
View patch

Vendor Advisories (1)

microsoft2021-May/CVE-2021-28478Important

Microsoft SharePoint Server Spoofing Vulnerability

May 11, 2021

References

portal.msrc.microsoft.com / en-US/security-guidance/advisory/CVE-2021-28478
PatchVendor Advisory