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CVE-2021-34451
Microsoft Office Online Server Spoofing Vulnerability
Medium5.3EPSS 1.8%
- Published
- Updated
- Reserved
- Assigned by
- microsoft
Description
Microsoft Office Online Server Spoofing Vulnerability
Timeline
ID reserved
By microsoft
- 37 days later
· 37 days later
Published
- 5 years later
· 5 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| microsoftCNA (assigner) | 3.1 | Medium5.3 | 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 |
| NVDNVD · Modified | 3.1 | Medium5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N |
- EPSS (exploitation in 30 days)
- 1.8% · top 22% of all CVEs (7 Nov 2026)
Loading the EPSS history…
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.3.
Weakness
- Spoofing
Affected products
Microsoft · Microsoft Office Online Server
- affected 16.0.1 – < 16.0.10376.20001
References (2)
- Microsoft Office Online Server Spoofing Vulnerability (opens in a new tab)vendor-advisorypatch
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34451 (opens in a new tab)x_refsource_MISCx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2021-34451)Record last updated .