CVE-2026-55120 – Microsoft PowerPoint Remote Code Execution Vulnerability

A heap-based buffer overflow vulnerability in Microsoft PowerPoint allows an unauthorized attacker to execute arbitrary code on a local system. Successful exploitation requires a user to open a specially crafted PowerPoint presentation. Microsoft has released security updates for affected PowerPoint and Microsoft Office products.

CVSS Score: 7.8

SEVERITY: Critical

THREAT:
This vulnerability allows an attacker to execute arbitrary code by convincing a user to open a specially crafted PowerPoint presentation. Malicious presentation files can be delivered through phishing emails, file-sharing services, or collaboration platforms. If exploited, the attacker can execute code with the privileges of the current user, potentially leading to malware installation, credential theft, data compromise, or additional attacks within the environment.

EXPLOITS:
At the time of publication, the vulnerability has not been publicly disclosed and Microsoft has not detected active exploitation. Microsoft assesses exploitation as less likely. The CVSS v3.1 temporal metrics list exploit code maturity as Unproven, and the provided information does not confirm the existence of publicly available proof-of-concept exploit code.

TECHNICAL SUMMARY:
The vulnerability is caused by a heap-based buffer overflow (CWE-122) in Microsoft PowerPoint. A specially crafted presentation file can trigger memory corruption, allowing arbitrary code execution. Although categorized as a Remote Code Execution vulnerability, Microsoft explains that the attack itself is carried out locally after a user opens the malicious presentation.

EXPLOITABILITY:
Affected products include Microsoft 365 Apps for Enterprise (32-bit and 64-bit), Microsoft PowerPoint 2016 (32-bit and 64-bit), Microsoft Office 2019, Microsoft Office 365 for Mac, Microsoft Office LTSC 2021, Microsoft Office LTSC 2024, Microsoft Office LTSC for Mac 2021, and Microsoft Office LTSC for Mac 2024. For Microsoft Office LTSC 2021 and LTSC 2024, the affected software table lists the CVSS score set as N/A for those products. Exploitation requires no attacker privileges but does require user interaction, specifically opening a specially crafted PowerPoint presentation.

BUSINESS IMPACT:
PowerPoint presentations are frequently exchanged for business communications, training, and external collaboration, making them an attractive delivery mechanism for phishing attacks. Successful exploitation could allow attackers to execute malicious code, deploy ransomware, steal sensitive information, or establish persistence within the environment.

WORKAROUND:
No mitigations or workarounds are available. Microsoft recommends installing the appropriate security updates for all affected PowerPoint and Microsoft Office products.

URGENCY:
This vulnerability should be deployed urgently because it is rated Critical. Although user interaction is required, malicious presentation files remain an effective delivery method for malware. Prompt deployment of the available security updates significantly reduces the risk of compromise.