Reachable assertion in Linux kernel - CVE-2026-63806
Published: July 21, 2026
Vulnerability identifier: #VU138846
CSH Severity: Low
CVSS v4: 5.7 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-63806
CWE-ID: CWE-617
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to an improper handling of unaligned memory access in ioeventfd datamatch handling in KVM when processing a guest store that splits a page and targets emulated MMIO with a datamatch-enabled ioeventfd. A local user can trigger a specially crafted guest store operation to cause a denial of service.
Exploitation requires a guest configuration where the second page contains a datamatch-enabled ioeventfd at offset 0.
Affected software
Linux kernel
How to mitigate CVE-2026-63806
Install security update from vendor's repository.
Linux kernel - update to 7.0 rc3