CVE-2026-20602 is a denial-of-service vulnerability affecting Apple macOS operating systems, identified as a resource exhaustion issue (CWE-400) caused by improper handling of caches. This flaw allows a local application with limited privileges to trigger a denial-of-service condition by exploiting the way the system manages cache resources, potentially leading to system instability or crashes. The vulnerability does not impact confidentiality or integrity but severely affects availability. It requires local access with low privileges and does not need user interaction, making it easier for malicious or compromised apps to exploit once local access is obtained. The issue was addressed by Apple through improved cache handling mechanisms in macOS Sequoia 15.7.4, macOS Tahoe 26.3, and macOS Sonoma 14.8.4. While no public exploits have been reported, the vulnerability poses a risk to system reliability, especially in environments where macOS devices are used for critical operations. The CVSS v3.1 base score of 5.5 reflects a medium severity, considering the local attack vector, low complexity, and high impact on availability. Organizations should prioritize patching affected systems to prevent potential denial-of-service disruptions.

The primary impact of CVE-2026-20602 is on system availability, as exploitation can cause denial-of-service conditions by exhausting cache resources or triggering system crashes. This can disrupt business operations, especially in environments relying heavily on macOS devices for critical tasks, such as creative industries, software development, and enterprise environments using Apple hardware. Although the vulnerability does not compromise confidentiality or integrity, repeated or targeted exploitation could lead to significant downtime, loss of productivity, and potential cascading effects on dependent services. The requirement for local access limits remote exploitation, but insider threats or malware with local execution capabilities could leverage this vulnerability. Organizations with large macOS deployments or those in sectors requiring high availability should consider this a moderate risk until patched.

1. Apply the official patches released by Apple immediately: upgrade to macOS Sequoia 15.7.4, macOS Tahoe 26.3, or macOS Sonoma 14.8.4 as applicable. 2. Restrict local application installation and execution privileges to trusted users and software to reduce the risk of local exploitation. 3. Implement endpoint protection solutions that monitor for unusual application behavior indicative of resource exhaustion attacks. 4. Employ system monitoring to detect abnormal cache usage or system instability that could signal exploitation attempts. 5. Educate users about the risks of running untrusted applications locally and enforce strict application whitelisting policies. 6. Regularly audit and limit local user privileges to minimize the attack surface. 7. Maintain up-to-date backups and incident response plans to quickly recover from potential denial-of-service incidents.