Multiple security vulnerabilities have been identified in the Xen hypervisor, affecting version 4.5. The issues involve the grant copy mechanism used to copy data between virtual machines and can allow a malicious guest to access memory belonging to other guests, including the privileged management domain. This creates a serious risk to host isolation and the confidentiality and integrity of workloads running on the same physical system.
CVE-2026-102703: This flaw is in the Xen hypervisor grant copy operation, where permission checks for memory pages can be reused without revalidation in certain batch-copy cases. A malicious guest virtual machine can exploit the missing recheck to read or write memory belonging to other virtual machines, including the privileged management domain.[/subscribe_to_unlock_form]
Multiple security vulnerabilities have been identified in the Xen hypervisor, affecting version 4.5. The issues involve the grant copy mechanism used to copy data between virtual machines and can allow a malicious guest to access memory belonging to other guests, including the privileged management domain. This creates a serious risk to host isolation and the confidentiality and integrity of workloads running on the same physical system.
CVE-2026-102703: This flaw is in the Xen hypervisor grant copy operation, where permission checks for memory pages can be reused without revalidation in certain batch-copy cases. A malicious guest virtual machine can exploit the missing recheck to read or write memory belonging to other virtual machines, including the privileged management domain.[emaillocker id="1283"]
CVE-2026-102704: This second grant copy flaw also allows a malicious guest virtual machine to bypass the hypervisor's memory permission enforcement during cross-VM copy operations. The attacker can access memory that is not owned by its own virtual machine, potentially compromising other guests and the privileged management domain on the same host.
These vulnerabilities collectively present a serious threat to Xen-based virtualization environments, particularly hosts that run untrusted or multi-tenant guest virtual machines alongside privileged management workloads. The most at-risk systems are those where a single compromised guest could reach memory outside its isolation boundary. They should be treated as urgent security concerns requiring prompt attention.
The following reports contain further technical details:
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