Summary
Impact: Remote Code Execution. Microsoft rating: Important. Not known to be exploited — Exploitation Unlikely. Customer action: Required.
Details
According to the CVSS metric, the attack complexity is high (AC:H). What does that mean for this vulnerability?
Successful exploitation of this vulnerability requires an attacker to win a race condition.
According to the CVSS metric, the attack vector is local (AV:L). Why does the CVE title indicate that this is a remote code execution?
The word Remote in the title refers to the location of the attacker. This type of exploit is sometimes referred to as Arbitrary Code Execution (ACE). The attack itself is carried out locally. This means an attacker or victim needs to execute code from the local machine to exploit the vulnerability.
According to the CVSS metric, user interaction is required (UI:R). What interaction would the user have to do?
An attacker must send a user a malicious Office file and convince them to open it.
Security updates
10.0.26100.7463 — https://learn.microsoft.com/en-us/windows/apps/windows-sdk/release-notes
Vulnerabilities 1
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High 7.0
Inbox COM Objects (Global Memory) Remote Code Execution Vulnerability
Use after free in Inbox COM Objects allows an unauthorized attacker to execute code locally.
Revision history
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#1
Information published.
References
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CVE-2026-21219 Inbox COM Objects (Global Memory) Remote Code Execution Vulnerability - HTML
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21219
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Microsoft Exploitability Index
https://www.microsoft.com/en-us/msrc/exploitability-index?rtc=1
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Microsoft Support Lifecycle
https://support.microsoft.com/lifecycle
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Common Vulnerability Scoring System
https://www.first.org/cvss