CVE-2026-21511

CWE-502 — Deserialization of Untrusted Data5 documents5 sources
Severity
7.5HIGH
EPSS
0.2%
top 54.47%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
14
Microsoft Microsoft 365 Apps FOR EnterpriseMicrosoft Microsoft Office 2019Microsoft Microsoft Office Ltsc 2021+11 more
Timeline
PublishedFeb 10

Description

Deserialization of untrusted data in Microsoft Office Outlook allows an unauthorized attacker to perform spoofing over a network.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:NExploitability: 3.9 | Impact: 3.6

Affected Packages14 packages

▶CVEListV5microsoft/microsoft_office_201919.0.0 — https://aka.ms/OfficeSecurityReleases
▶CVEListV5microsoft/microsoft_office_ltsc_202116.0.1 — https://aka.ms/OfficeSecurityReleases
▶CVEListV5microsoft/microsoft_office_ltsc_202416.0.0 — https://aka.ms/OfficeSecurityReleases
▶CVEListV5microsoft/microsoft_office_ltsc_for_mac_202116.0.1 — 16.106.26020821
▶CVEListV5microsoft/microsoft_office_ltsc_for_mac_202416.0.0 — 16.106.26020821

🔴Vulnerability Details

2
GHSA
GHSA-x27j-2rq3-h4mw: Deserialization of untrusted data in Microsoft Office Outlook allows an unauthorized attacker to perform spoofing over a network↗2026-02-10
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CVEList
Microsoft Outlook Spoofing Vulnerability↗2026-02-10
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📋Vendor Advisories

1
Microsoft
Microsoft Outlook Spoofing Vulnerability↗2026-02-10
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🕵️Threat Intelligence

1
Wiz
CVE-2026-21511 Impact, Exploitability, and Mitigation Steps | Wiz↗
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