An out-of-bounds write flaw has been identified in macOS, caused by inadequate bounds checking that could allow a malicious application to write outside the intended memory area. This type of memory corruption can lead to arbitrary memory damage and results in the operating system terminating unexpectedly, representing a denial‑of‑service condition. The weakness is classified as CWE‑787, reflecting a violation of proper bounds validation when accessing memory objects.

Apple’s macOS platform is affected, with versions released prior to macOS Sequoia 15.6 carrying the vulnerability. The fix incorporates improved bounds checking and is available in Sequoia 15.6 and later releases, so any older macOS distribution remains at risk.

The CVSS score of 9.8 indicates a critical severity, while the EPSS score of less than 1 % suggests a low predicted exploitation probability at present. The vulnerability is not listed in the CISA KEV catalog. Based on the description, it is inferred that an attacker would need to run a malicious application on the target machine to trigger the out-of-bounds write, implying a local execution requirement. The risk therefore primarily applies to environments where untrusted or elevated applications can run on macOS systems.