CVE-2021-34451
Microsoft Office Online Server Spoofing Vulnerability
Microsoft Office Online Server Spoofing Vulnerability
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- Low
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Microsoft Office Online Server Spoofing Vulnerability
Microsoft Office Online Server Spoofing Vulnerability
- Record
CVE-2021-34451- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N/E:U/RL:O/RC:C - Updated
- 2026-11-02
EUVDEUVD-2021-21106
Microsoft Office Online Server Spoofing Vulnerability
- Record
EUVD-2021-21106- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N/E:U/RL:O/RC:C - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-pvgh-q9cp-r848
Microsoft Office Online Server Spoofing Vulnerability
Microsoft Office Online Server Spoofing Vulnerability
- Record
GHSA-pvgh-q9cp-r848- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - Updated
- 2026-11-02
NVD
Microsoft Office Online Server Spoofing Vulnerability
- Record
CVE-2021-34451- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - CVSS 2.0
- 5.0 Medium
AV:N/AC:L/Au:N/C:N/I:P/A:N - Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-34451 is a medium vulnerability (CVSS 5.3) in Microsoft Office Online Server, published July 16, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.78%, the 78th percentile. No source names a fixed version.