CVE-2026-89919

A flaw was found in the Linux kernel's Kernel-based Virtual Machine (KVM) component for s390 architecture. This vulnerability occurs due to improper synchronization when handling memory management unit (MMU) locks. Specifically, concurrent operations related to key operations and virtual machine memory limit size can lead to the use of outdated memory mapping information. This can result in memory corruption within the system.

KVM s390 keyop can read gmap asce outside the mmu_lock read side while a concurrent KVM_S390_VM_MEM_LIMIT_SIZE operation updates the same value under the write side of the lock. This race can make KVM_S390_KEYOP walk memory using a stale address space control value and the upstream description states that this can result in memory corruption. For the CVSS the PR:L is selected because reliable triggering requires local access to KVM ioctls from a user or service that can run or control a VM, but it does not require full host root in many deployments. The issue is not directly network reachable and applies to s390 KVM hosts where these ioctls are available. Impact is at least a local denial of service via memory corruption and in worst case may allow confidentiality or integrity impact or privilege escalation, so it should be reviewed manually.

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.

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.