5.3

CVE-2021-34451: microsoft microsoft office online server

CVSS: 5.3v3.1MediumModified
Published 16-07-2021Last modified 10-08-2026
Open JSON

Vulnerability summary

CVE-2021-34451 is a medium (CVSS 5.3) vulnerability in microsoft microsoft office online server. EPSS estimates a 1.78% chance of exploitation in the next 30 days, higher than 77.9% of scored vulnerabilities.

Overall risk
22/100
0100
Low · default modelHow is this calculated?
CVSS score
5.3/10
010
Medium · v3.1 (CVE.org)
EPSS score
1.78%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 16-07-2021
    PublishedVulnerability first disclosed.
  2. 10-08-2026
    Last modifiedVulnerability information updated.

Description

Microsoft Office Online Server Spoofing Vulnerability

CVSS metrics

3 scores · 2 sources · 2 versions

EPSS trend

Probability

1.78%

Chance of exploitation in the next 30 days

Percentile

78%

Versus all other CVEs

30-day change

0.00 pp

From 1.78% on 20-09-2026

20-09-202620-10-2026
EPSS score
1.78%

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

No weakness data has been published for this record.

Affected systems

Microsoft2 products

1 vendor · 2 products

References

2 links