CVE-2026-21219: Inbox COM Objects (Global Memory) Remote Code Execution Vulnerability

Overview

Severity
High (CVSS 7)
CVSS Vector
CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Category
Remote Code Execution
Exploit Status
Not Exploited
Exploitation Likelihood
Unlikely
Patch Tuesday
2026-Jan
Released
2026-01-13
EPSS Score
0.07% (percentile: 22.1%)

Description

Use after free in Inbox COM Objects allows an unauthorized attacker to execute code locally.

FAQ

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.

Affected Products (1)

Developer Tools

  • Windows SDK

Security Updates (1)

Acknowledgments

Zhiniang Peng with HUST & R4nger with CyberKunLun

Revision History

  • 2026-01-13: Information published.