Bug 2516584 (CVE-2026-72279)

Summary: CVE-2026-72279 kernel: KVM: arm64: nv: Respect read-only PFN when mapping L1 VNCR
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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Hardware: All   
OS: Linux   
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A flaw was found in the KVM (Kernel-based Virtual Machine) component of the Linux kernel. KVM on arm64 architectures incorrectly maps the L1 Virtual Nested Control Register (VNCR) into the host stage-1, failing to respect read-only memory regions. This could allow a malicious guest to write to a protected memory area, resulting in a page leak and potential information disclosure.
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Description OSIDB Bzimport 2026-08-15 06:20:16 UTC 
In the Linux kernel, the following vulnerability has been resolved:

KVM: arm64: nv: Respect read-only PFN when mapping L1 VNCR

KVM currently maps the L1 VNCR into the host stage-1 by relying entirely
on the permissions of the guest stage-1. At the same time, it is
entirely possible that the backing PFN is read-only (e.g. RO memslot),
meaning that the L1 VNCR should use at most a read-only mapping.

Cache the writability of the PFN in the VNCR TLB and use it to constrain
the resulting fixmap permissions. Promote VNCR permission faults to an
SEA in the case where the guest attempts to write to a read-only
endpoint. Conveniently, this also plugs a page leak found by Sashiko [*]
resulting from the early return for a read-only PFN.
Comment 1 Keith Grant 2026-08-18 18:42:13 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081558-CVE-2026-72279-ee48@gregkh/T