Deserialization Flaw in Microsoft Dynamics NAV Permits Remote Code Execution

Executive Summary

CVE-2026-55944 is a vulnerability in Microsoft Dynamics NAV that involves the deserialization of untrusted data. Deserialization is a process where data received over a network or from another source is converted back into an object or data structure that a program can use. In this case, the vulnerability allows an unauthorized attacker to send specially crafted data to the system, which, when deserialized, can execute arbitrary code on the affected system.

This type of vulnerability is particularly dangerous because it can be exploited remotely without requiring any authentication or user interaction. The attacker does not need to have prior access to the system or any credentials to exploit it.

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Detection Guidance

The provided context does not include specific detection methods or commands for identifying the deserialization of untrusted data vulnerability in Microsoft Dynamics NAV (CVE-2026-55944).

Generally, detecting deserialization vulnerabilities may involve monitoring network traffic for unusual data patterns or using security tools to scan for vulnerable software versions. However, no explicit guidance is available in the given resources.

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Impact Analysis

The impact of CVE-2026-55944 can be severe due to its potential for remote code execution (RCE). Here are the possible impacts:

• An attacker could gain full control over the affected Microsoft Dynamics NAV system, allowing them to execute commands, install malware, or steal sensitive data.
• The vulnerability could be used to move laterally within a network, compromising other systems and expanding the attacker's access.
• Since the attack can be carried out over a network without authentication, it poses a significant risk to organizations relying on Microsoft Dynamics NAV for critical business operations.
• The CVSS base score of 9.8 (Critical) indicates a high potential for damage, including confidentiality, integrity, and availability impacts.

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Compliance Impact

This vulnerability can have significant implications for compliance with various standards and regulations, depending on how Microsoft Dynamics NAV is used within an organization:

• GDPR (General Data Protection Regulation): If the affected system processes or stores personal data of EU citizens, a breach resulting from this vulnerability could lead to unauthorized access or disclosure of that data. This may violate GDPR requirements for data protection and could result in hefty fines or legal action.
• HIPAA (Health Insurance Portability and Accountability Act): For organizations in the healthcare sector, if Microsoft Dynamics NAV is used to handle protected health information (PHI), exploitation of this vulnerability could lead to unauthorized access to PHI. This would constitute a breach under HIPAA, potentially resulting in penalties and mandatory breach notifications.
• Other standards like PCI DSS (Payment Card Industry Data Security Standard): If the system processes payment card information, a breach could violate PCI DSS requirements, leading to fines, increased scrutiny, or loss of payment processing capabilities.

Organizations must ensure they apply the necessary patches or mitigations to address this vulnerability to maintain compliance with these regulations and avoid potential legal or financial consequences.

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Mitigation Strategies

The provided context does not include specific mitigation steps for CVE-2026-55944. However, based on the nature of the vulnerability (deserialization of untrusted data), the following general steps may help mitigate the risk:

• Apply the latest security updates or patches provided by Microsoft for Microsoft Dynamics NAV. Refer to the official Microsoft update guide for this CVE.
• Restrict network access to Microsoft Dynamics NAV instances to trusted users and systems only.
• Monitor network traffic for suspicious deserialization attempts or unauthorized access attempts.
• Review Microsoft's official guidance for CVE-2026-55944, as it may include specific workarounds or additional mitigation steps.

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