8.1

CVE-2021-34520: microsoft microsoft sharepoint enterprise server 2016 Deserialization of Untrusted Data

CVSS: 8.1v3.1HighModified
Published 14-07-2021Last modified 10-08-2026
Open JSON

Vulnerability summary

CVE-2021-34520 is a high (CVSS 8.1) Deserialization of Untrusted Data vulnerability in microsoft microsoft sharepoint enterprise server 2016. EPSS estimates a 4.42% chance of exploitation in the next 30 days, higher than 91.3% of scored vulnerabilities.

Overall risk
33/100
0100
Medium · default modelHow is this calculated?
CVSS score
8.1/10
010
High · v3.1 (CVE.org)
EPSS score
4.42%
0%100%
Low · +0.04 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 14-07-2021
    PublishedVulnerability first disclosed.
  2. 10-08-2026
    Last modifiedVulnerability information updated.

Description

Microsoft SharePoint Server Remote Code Execution Vulnerability

CVSS metrics

3 scores · 2 sources · 2 versions

EPSS trend

Probability

4.42%

Chance of exploitation in the next 30 days

Percentile

91%

Versus all other CVEs

30-day change

+0.04 pp

From 4.39% on 21-09-2026

21-09-202621-10-2026
EPSS score
4.42%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Microsoft5 products

1 vendor · 5 products

References

3 links