Security vulnerabilities are a common occurrence in managing any business’s organizational security. The prompt patching and remediation of any new vulnerabilities are critical to reducing the outside attack surface. Netizen’s Security Operations Center (SOC) has compiled five critical vulnerabilities from December that should be immediately patched or addressed if present in your environment. Detailed writeups below:
CVE-2025-21366
CVE-2025-21366 is a high-severity remote code execution (RCE) vulnerability affecting Microsoft Access. This flaw, disclosed in Microsoft’s January 2025 Patch Tuesday, poses a significant risk as it could allow an attacker to execute arbitrary code on a targeted system.
The vulnerability is rated with a CVSS v3 base score of 7.8, indicating a serious threat, particularly in environments where Microsoft Access is widely used for database management. Exploitation of CVE-2025-21366 requires user interaction, meaning an attacker would likely need to convince a user to open a malicious file or perform an action that triggers the vulnerability. Once exploited, the attacker could gain high privileges on the affected system, leading to potential data compromise, unauthorized system modifications, or further exploitation of the network.
Microsoft has released a security update to address CVE-2025-21366, and organizations are strongly advised to apply the patch as soon as possible to mitigate the risk. Given the potential for exploitation and the widespread use of Microsoft Access in enterprise environments, timely remediation is crucial to prevent security breaches.
CVE-2025-21333
CVE-2025-21333 is a high-severity elevation of privilege vulnerability affecting Windows Hyper-V’s NT Kernel Integration VSP. This flaw, disclosed as part of Microsoft’s January 2025 Patch Tuesday, is particularly concerning as it could allow an attacker to escalate privileges within a virtualized environment, potentially compromising the host system.
With a total of 157 vulnerabilities addressed in this patch cycle—the largest ever for a Microsoft Patch Tuesday—CVE-2025-21333 stands out due to its impact on virtualized infrastructures. The vulnerability exists in Hyper-V’s integration services, which facilitate communication between guest virtual machines and the host operating system. If exploited, an attacker with limited access to a virtual machine could leverage this flaw to execute code with elevated privileges, potentially affecting other virtual machines or the underlying Hyper-V host.
Organizations relying on Hyper-V for virtualization should prioritize applying this patch to prevent potential privilege escalation attacks that could compromise their cloud or on-premises virtual environments. Given the critical nature of this vulnerability and its potential to be chained with other exploits, timely remediation is strongly recommended.
CVE-2025-0282
CVE-2025-0282 is a critical stack-based buffer overflow vulnerability affecting Ivanti Connect Secure, Policy Secure, and Neurons for ZTA gateways. The flaw, present in Ivanti Connect Secure before version 22.7R2.5, Policy Secure before version 22.7R1.2, and Neurons for ZTA gateways before version 22.7R2.3, allows a remote unauthenticated attacker to achieve remote code execution (RCE).
Ivanti disclosed this vulnerability alongside another related flaw, revealing that CVE-2025-0282 had already been actively exploited as a zero-day before the official disclosure. This means that attackers were leveraging the vulnerability in real-world attacks before security patches were available. The flaw enables attackers to execute arbitrary code on vulnerable systems, potentially leading to full system compromise, data exfiltration, and further network infiltration.
Given its critical severity and the fact that exploitation has been observed in the wild, organizations using affected Ivanti products should prioritize immediate patching. Delays in remediation could leave enterprises at significant risk, especially considering that high-profile targets, such as national infrastructure and enterprises, have already been affected. Security researchers have warned that many Ivanti VPNs remain unpatched despite the availability of fixes, further increasing the urgency for administrators to deploy the necessary updates as soon as possible.
CVE-2025-21275
CVE-2025-21275 is a high-severity elevation of privilege vulnerability affecting the Windows App Package Installer. This flaw allows attackers with local access to escalate their privileges, potentially gaining control over a system. Exploiting this vulnerability does not require user interaction but does require prior access to the machine with limited privileges.
The vulnerability was disclosed as part of Microsoft’s January 2025 Patch Tuesday, which addressed a total of 157 CVEs. Given the nature of privilege escalation vulnerabilities, CVE-2025-21275 could be exploited as part of a larger attack chain, allowing adversaries to gain higher-level access on compromised systems.
Organizations and individual users should apply the security updates released by Microsoft as soon as possible to mitigate the risk. Delaying patching could leave systems vulnerable to attacks leveraging this flaw to gain unauthorized access and execute malicious actions with elevated privileges.
CVE-2025-21307
CVE-2025-21307 is a critical remote code execution vulnerability affecting the Windows Reliable Multicast Transport Driver (RMCAST). This flaw, with a CVSS v3 base score of 9.8, allows unauthenticated attackers to execute arbitrary code remotely without requiring user interaction. Due to its low attack complexity and high impact on confidentiality, integrity, and availability, this vulnerability poses a significant risk to affected systems.
Microsoft disclosed the issue as part of the January 2025 Patch Tuesday security updates, urging organizations to apply the necessary patches immediately. Given its critical severity, threat actors could exploit CVE-2025-21307 to deploy malware, disrupt services, or gain unauthorized access to networks.
Users and administrators should prioritize patching systems running vulnerable versions of Windows to mitigate potential exploitation. Unpatched systems remain highly susceptible to remote attacks, which could lead to full system compromise.
How Can Netizen Help?
Netizen ensures that security gets built-in and not bolted-on. Providing advanced solutions to protect critical IT infrastructure such as the popular “CISO-as-a-Service” wherein companies can leverage the expertise of executive-level cybersecurity professionals without having to bear the cost of employing them full time.
We also offer compliance support, vulnerability assessments, penetration testing, and more security-related services for businesses of any size and type.
Additionally, Netizen offers an automated and affordable assessment tool that continuously scans systems, websites, applications, and networks to uncover issues. Vulnerability data is then securely analyzed and presented through an easy-to-interpret dashboard to yield actionable risk and compliance information for audiences ranging from IT professionals to executive managers.
Netizen is an ISO 27001:2013 (Information Security Management), ISO 9001:2015, and CMMI V 2.0 Level 3 certified company. We are a proud Service-Disabled Veteran-Owned Small Business that is recognized by the U.S. Department of Labor for hiring and retention of military veterans.
Questions or concerns? Feel free to reach out to us any time –
https://www.netizen.net/contact
