Critical CVSS 9.9 EPSS 0.01954 2020-09 archive

Executive Summary

A remote code execution vulnerability exists in Microsoft SharePoint where APIs aren't properly protected from unsafe data input. An attacker who successfully exploited the vulnerability could run arbitrary code in the context of the SharePoint application pool and the SharePoint server farm account. Exploitation of this vulnerability requires that a user access a susceptible API on an affected version of SharePoint with specially-formatted input. The security update addresses the vulnerability by correcting how SharePoint handles deserialization of untrusted data.

Overview

9.9
CVSS CRITICAL
Critical
MS Severity
Not Exploited
MS Exploit Status
Less Likely
MS Exploit Likelihood
Category Remote Code Execution
Released Sep 8 2020
Last Updated Sep 8 2020
Publicly Disclosed No
CISA KEV Not Listed
Known Exploits None Known
EPSS Score 0.01954 — 0.7766 percentile
NVD CVSS 9.9 CRITICAL — matches MSRC

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:P/RL:O/RC:C
ATTACK VECTOR
Network
ATTACK COMPLEXITY
Low
PRIVILEGES REQUIRED
Low
USER INTERACTION
None
SCOPE
Changed
CONFIDENTIALITY
High
INTEGRITY
High
AVAILABILITY
High
EXPLOIT CODE MATURITY
Proof-of-Concept
REMEDIATION LEVEL
Official Fix
REPORT CONFIDENCE
Confirmed
Temporal Score: 8.9

EPSS Score

0.01954
probability of exploitation in the next 30 days
0.7766 percentile - updated 2026-06-21
View on FIRST.org

Affected Products

4 affected products
Product KB Article Severity Impact Restart Required
Microsoft SharePoint Enterprise Server 2013 Service Pack 1 4484515 (Security Update) Critical Remote Code Execution Maybe
Microsoft SharePoint Enterprise Server 2016 4484506 (Security Update) Critical Remote Code Execution Maybe
Microsoft SharePoint Foundation 2013 Service Pack 1 4484525 (Security Update) Critical Remote Code Execution Maybe
Microsoft SharePoint Server 2019 4484505 (Security Update) Critical Remote Code Execution Maybe

Patches

4 patches
Article Type Restart
4484515 Security Update Maybe
4484506 Security Update Maybe
4484525 Security Update Maybe
4484505 Security Update Maybe

Known Exploits

Acknowledgments

Markus Wulftange (@mwulftange)