CVE-2026-89919 KVM: s390: keyop: use mmu_lock to read gmap->asce
A race condition in KVM s390 keyop allows concurrent access to stale memory mappings, potentially leading to memory corruption and privilege escalation.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-89919?
CVE-2026-89919 is a high-severity vulnerability in Linux, published on 16 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
KVM: s390: keyop: use mmu_lock to read gmap->asce
Every other dat_* consumer in this file (kvm_s390_get_skeys, set_skeys, get_cmma_bits, set_cmma_bits, MEM_CLR_CMMA, kvm_s390_fixup_prefix, kvm_test_age_gfn, kvm_age_gfn) reads kvm->arch.gmap->asce *inside* the mmu_lock read-side. keyop is the only outlier.
gmap->asce is mutated under write_lock(mmu_lock) by gmap_set_limit() and keyop might use a stale asce value for walking as KVM_S390_KEYOP and KVM_S390_VM_MEM_LIMIT_SIZE can run concurrently. This can result in memory corruption.
Which versions are affected by CVE-2026-89919?
How do I fix CVE-2026-89919?
Apply the vendor's patch.
Is CVE-2026-89919 being exploited?
There is no known exploitation of CVE-2026-89919 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-89919, GHSA-xrcv-f2mv-23j2, UBUNTU-CVE-2026-89919.