CVE-2026-31568

A flaw was found in the Linux kernel. This vulnerability, located in the s390/mm component, is due to missing secure storage access fixups for memory donated to the Ultravisor. When secure storage access exceptions occur for such memory, the kernel can enter an unresolvable loop. This can lead to a system hang or crash, resulting in a Denial of Service (DoS).

This vulnerability is rated as Moderate severity because it is constrained to IBM Z (s390x) environments utilizing IBM Secure Execution and is limited to a local denial of service without compromising data confidentiality or system integrity. The flaw only arises when kernel page-fault handling encounters storage donated to the Ultravisor, leaving standard enterprise architectures unaffected. In these specific virtualization setups, unresolvable exception cycles can induce a host kernel hang or crash.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.