KVM is widely used in cloud and virtualization; this guest-to-host kernel memory bug can crash or compromise hosts, risking broad infrastructure disruption.
CVE-2026-63807
KVM kernel bug lets guest hugepage mappings cause host out-of-bounds access/crash.
Is CVE-2026-63807 being exploited?
Not confirmed. CVE-2026-63807 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 0.14% probability of exploitation in the next 30 days.
How severe is CVE-2026-63807?
CVE-2026-63807 is rated High with a CVSS score of 8.8. 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-2026-63807?
Yes. A fix has been recorded for CVE-2026-63807. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-63807 affect?
CVE-2026-63807 affects Linux kernel KVM (x86/mmu), Hosts running KVM/QEMU virtual machines. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-63807?
Install patched kernel, reboot hosts, and isolate untrusted VMs.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
A guest can trigger out-of-bounds access in the host KVM, causing host kernel panic/crash and possible guest-to-host code execution.
Immediate action required
- affected>= 9eba50f8d7fcb61774f160890f98239fa3ab68a6 and < 7b52008023b7facf40fba3ebe92449bda8ea53b9
- affected>= 9eba50f8d7fcb61774f160890f98239fa3ab68a6 and < 5cab1c989f938f5e1b9a0de66486f1fc2c28479b
- affected>= 9eba50f8d7fcb61774f160890f98239fa3ab68a6 and < 48b91ed7e22bb82571c34f8b80b6ecdc90a6fab8
- affected>= 9eba50f8d7fcb61774f160890f98239fa3ab68a6 and < c5c29b3c268332afe67d598a034c58344540ed92
- affected>= 9eba50f8d7fcb61774f160890f98239fa3ab68a6 and < 18587f9831612e24cd8f24be1ec15478feff7abc
- affected>= 9eba50f8d7fcb61774f160890f98239fa3ab68a6 and < b2ae3245ea44dccaa9af676b6747476951883318
- affected>= 9eba50f8d7fcb61774f160890f98239fa3ab68a6 and < ef057cbf825e03b63f6edf5980f96abf3c53089d
- affected5.12
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.