Kernel KVM SEV flaw enables guest-to-host compromise on widely used Linux virtualization stacks and cloud hosts; affects many organizations running VMs.
CVE-2026-63938
Linux KVM SEV buffer validation flaw allows guest-to-host kernel compromise.
Is CVE-2026-63938 being exploited?
Not confirmed. CVE-2026-63938 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.18% probability of exploitation in the next 30 days.
How severe is CVE-2026-63938?
CVE-2026-63938 is rated Critical with a CVSS score of 9.3. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-63938?
Yes. A fix has been recorded for CVE-2026-63938. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-63938 affect?
CVE-2026-63938 affects Linux kernel (KVM/SEV), Hosts running KVM hypervisor, AMD SEV-enabled guest environments. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-63938?
Apply vendor kernel/security updates ASAP; isolate or pause untrusted VMs until patched.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Guest-crafted PSC buffer can corrupt host kernel memory, enabling guest-to-host escape or arbitrary kernel code execution.
Immediate action required
- affected>= 9b54e248d2644be71cb394eb85f31ad99e023a05 and < 5198f70c09a5f6e9e5f5a0a2c6b388f24294b176
- affected>= 9b54e248d2644be71cb394eb85f31ad99e023a05 and < 75c8d1d7291268b479794fba5808971dc2f5eaf3
- affected>= 9b54e248d2644be71cb394eb85f31ad99e023a05 and < 505a3b94535583e4265360e2621734e355ef263d
- affected>= 9b54e248d2644be71cb394eb85f31ad99e023a05 and < 121d88de56bc5c0ba0ce2f6381af67f948a7e7c1
- affected6.11
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.