CVE-2025-55243: Microsoft OfficePlus Spoofing Vulnerability
CVE-2025-55243 is a spoofing vulnerability in Microsoft OfficePlus, rated Important by Microsoft, with a CVSS 3.1 base score of 7.5 (High). An attacker can exploit it remotely over the network, without any privileges and without user interaction. Microsoft has not reported exploitation in the wild and rates exploitation as less likely. The EPSS model estimates a 1.16% probability of exploitation activity in the next 30 days, higher than 67% of all scored vulnerabilities. Microsoft released the fix on 9 September 2025 in the September 2025 Patch Tuesday. It affects 1 product in 1 product family (Microsoft Office).
Microsoft scores CVE-2025-55243 at 7.5 (temporal 6.5) using CVSS 3.1. Vector: 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
Metric
Value
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
None
Availability impact
None
Exploit code maturity
Unproven
Remediation level
Official fix
Report confidence
Confirmed
Description
Exposure of sensitive information to an unauthorized actor in Microsoft Office Plus allows an unauthorized attacker to perform spoofing over a network.