Microsoft Outlook Remote Code Execution Vulnerability (CVE-2025-62562)
Overview:
Microsoft has released security updates addressing a critical remote code execution (RCE) vulnerability in Microsoft Outlook and related Microsoft Office products. The vulnerability, tracked as CVE-2025-62562, arises from a use-after-free memory handling flaw and could allow an attacker to execute arbitrary code on a victim’s system.
The issue was disclosed and patched on December 9, 2025 and is rated Important with a CVSS score of 7.8. While exploitation requires user interaction, the vulnerability presents a realistic threat due to the prevalence of social engineering attacks via email.
Microsoft has confirmed that patches are available for most affected Windows-based Office products. Updates for certain Mac editions are pending.
How It Affects Systems:
The vulnerability is triggered when a user interacts with a specially crafted email:
- An attacker sends a maliciously crafted email to the victim.
- The exploit is triggered only when the user replies to the email.
- Upon replying, the use-after-free flaw can be exploited to execute attacker-controlled code.
Notably:
- The Outlook Preview Pane is not vulnerable.
- Simply viewing or previewing the email does not trigger exploitation.
- User interaction is required, increasing reliance on social engineering.
Who It Affects:
The vulnerability affects multiple Microsoft Office and SharePoint products, including both 32-bit and 64-bit editions:
Affected Products:
- Microsoft Word 2016 (32-bit & 64-bit)
- Microsoft Office 2019
- Microsoft Office LTSC 2021
- Microsoft Office LTSC 2024
- Microsoft 365 Apps for Enterprise
- Microsoft SharePoint Server 2019
- Microsoft SharePoint Enterprise Server 2016
- Microsoft Office LTSC for Mac 2021 (patch pending)
- Microsoft Office LTSC for Mac 2024 (patch pending)
Organizations using Outlook as part of these Office suites are particularly at risk.
Impact:
If successfully exploited, this vulnerability could allow an attacker to:
- Execute arbitrary code with the privileges of the logged-in user
- Install malware or backdoors
- Access or modify sensitive data
- Use compromised systems as a pivot point for lateral movement within the network
Although exploitation requires user interaction, the attack is considered practical in real-world environments, especially where phishing and email-based social engineering are common.
As of publication:
- There is no evidence of active exploitation
- No public exploit code has been reported
Recommendations - Immediate Actions:
- Apply Security Updates Immediately
- Deploy Microsoft’s released patches via:
- Windows Update
- Microsoft Download Center
- Ensure both 32-bit and 64-bit editions are patched.
- For Word 2016, verify systems are updated to build 16.0.5530.1000 or later.
- Deploy Microsoft’s released patches via:
- Prioritize Patch Deployment
- Enterprise administrators should roll out updates across all affected endpoints and servers in accordance with internal patch management policies.
Temporary Mitigations (If Patches Are Not Available)
- Advise users to:
- Avoid replying to unsolicited or suspicious emails
- Treat unexpected messages, especially those prompting replies, with caution
- Reinforce phishing awareness training
Mac Systems
- Monitor Microsoft advisories for the release of patches for:
- Microsoft Office LTSC for Mac 2021
- Microsoft Office LTSC for Mac 2024
- Apply updates as soon as they become available