CVE-2024-21385 is a high-severity use-after-free vulnerability (CWE-416) identified in the Chromium-based Microsoft Edge browser. This vulnerability allows an attacker to perform an elevation of privilege attack by exploiting improper memory management within the browser. Specifically, a use-after-free condition occurs when the browser attempts to access memory that has already been freed, leading to undefined behavior that can be leveraged to execute arbitrary code with elevated privileges. The vulnerability affects version 1.0.0 of Microsoft Edge (Chromium-based) and was published on January 26, 2024. The CVSS v3.1 base score is 8.3, indicating a high impact with the vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C. This means the attack can be performed remotely over the network (AV:N) but requires high attack complexity (AC:H), no privileges (PR:N), and user interaction (UI:R). The scope is changed (S:C), implying that the vulnerability affects resources beyond the initially vulnerable component. The impact on confidentiality, integrity, and availability is high (C:H/I:H/A:H). No known exploits are currently in the wild, and no patches have been linked yet. The vulnerability could be triggered by convincing a user to visit a malicious website or interact with crafted content, leading to potential full system compromise or unauthorized privilege escalation within the browser context. Given the widespread use of Microsoft Edge in enterprise and consumer environments, this vulnerability represents a significant risk if exploited.

For European organizations, this vulnerability poses a substantial risk due to the prevalent use of Microsoft Edge as a default or recommended browser in many corporate environments. Successful exploitation could lead to unauthorized access to sensitive corporate data, disruption of services, or lateral movement within internal networks. The elevation of privilege aspect means attackers could bypass security controls and gain higher-level access, potentially compromising endpoint security and leading to data breaches or ransomware deployment. The requirement for user interaction (e.g., visiting a malicious site) means phishing or social engineering campaigns could be effective vectors. Given the high confidentiality, integrity, and availability impacts, organizations handling sensitive personal data (e.g., financial institutions, healthcare providers) or critical infrastructure are particularly at risk. Additionally, the changed scope indicates that the vulnerability could affect components beyond the browser sandbox, increasing the potential damage. The absence of known exploits in the wild currently provides a window for proactive mitigation, but the high severity score necessitates urgent attention.

European organizations should implement a multi-layered mitigation strategy: 1) Monitor for official Microsoft Edge updates and apply patches immediately once available, as no patch links are currently provided. 2) Employ browser security policies to restrict or block access to untrusted websites and disable unnecessary browser extensions that could increase attack surface. 3) Enhance user awareness training focusing on phishing and social engineering to reduce the likelihood of user interaction with malicious content. 4) Utilize endpoint detection and response (EDR) solutions to monitor for suspicious browser behaviors indicative of exploitation attempts. 5) Consider deploying application control or sandboxing technologies to limit the impact of potential exploitation. 6) Network-level protections such as web filtering and intrusion prevention systems should be configured to detect and block known malicious URLs or payloads targeting this vulnerability. 7) Conduct regular vulnerability assessments and penetration testing to identify and remediate any exposure related to this vulnerability. 8) For critical environments, consider temporarily restricting Microsoft Edge usage or enforcing alternative browsers with no known vulnerabilities until patches are applied.