Out-of-bounds read in Linux kernel - CVE-2026-63807

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Main Vulnerability Database Vulnerabilities #VU138847

Out-of-bounds read in Linux kernel - CVE-2026-63807

Published: July 21, 2026


Vulnerability identifier: #VU138847
CSH Severity: Low
CVSS v4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-63807
CWE-ID: CWE-125
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 out-of-bounds access in the KVM x86 shadow MMU hugepage recovery logic when recovering hugepages for a direct shadow page whose gfn falls outside the target memslot. A local user can create a guest hugepage mapping that extends below the bounds of a memslot to cause a denial of service.

The issue can manifest as a host page fault in kernel mode during hugepage recovery.


Affected software

Linux kernel
Red Hat Enterprise Linux for x86_64 - Extended Update Support
Red Hat Enterprise Linux for IBM z Systems - Extended Update Support
Red Hat Enterprise Linux for Power, little endian - Extended Update Support
Red Hat Enterprise Linux for ARM 64 - Extended Update Support
Red Hat CodeReady Linux Builder for x86_64 - Extended Update Support
Red Hat CodeReady Linux Builder for Power, little endian - Extended Update Support
Red Hat CodeReady Linux Builder for IBM z Systems - Extended Update Support
Red Hat CodeReady Linux Builder for ARM 64 - Extended Update Support
kernel (Red Hat package)

How to mitigate CVE-2026-63807

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
kernel (Red Hat package) - update to 6.12.0-55.94.1.el10_0

External References

Related Security Bulletins