CVE-2026-21511
Microsoft Outlook Spoofing Vulnerability
Deserialization of untrusted data in Microsoft Office Outlook allows an unauthorized attacker to perform spoofing over a network.
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
- High
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Microsoft Outlook Spoofing Vulnerability
Deserialization of untrusted data in Microsoft Office Outlook allows an unauthorized attacker to perform spoofing over a network.
- Record
CVE-2026-21511- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C - Weakness
- CWE-502
- Updated
- 2026-11-02
EUVDEUVD-2026-7331
Deserialization of untrusted data in Microsoft Office Outlook allows an unauthorized attacker to perform spoofing over a network.
- Record
EUVD-2026-7331- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-x27j-2rq3-h4mw
Deserialization of untrusted data in Microsoft Office Outlook allows an unauthorized attacker to...
Deserialization of untrusted data in Microsoft Office Outlook allows an unauthorized attacker to perform spoofing over a network.
- Record
GHSA-x27j-2rq3-h4mw- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N - Weakness
- CWE-502
- Updated
- 2026-11-02
NVD
Deserialization of untrusted data in Microsoft Office Outlook allows an unauthorized attacker to perform spoofing over a network.
- Record
CVE-2026-21511- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N - Weakness
- CWE-502
- Updated
- 2026-11-02
Affected products
- microsoft office
- microsoft 365 apps
- microsoft 365 apps for enterprise
- microsoft office 2019
- microsoft office ltsc 2021
- microsoft office ltsc 2024
- microsoft office ltsc for mac 2021
- microsoft office ltsc for mac 2024
- microsoft sharepoint enterprise server 2016
- microsoft sharepoint server 2019
- microsoft sharepoint server subscription edition
- microsoft word 2016
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-2026-21511 is a high vulnerability (CVSS 7.5) in Microsoft Office, published February 10, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 3.97%, the 90th percentile. No source names a fixed version.