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ITScape: Guest-to-host escape in KVM/arm64 vGIC-ITS

IdentifiersCVE-2026-46316CWE-416

CVE-2026-46316, dubbed ITScape, is a Linux kernel vulnerability in KVM on arm64 affecting the in-kernel vGIC-ITS emulation, specifically vgic_its_invalidate_cache(). The bug is caused by a race during concurrent invalidation of the per-ITS translation cache. The function iterates cache entries with xa_for_each() and drops references with vgic_put_irq(), but historically put the iterated pointer rather than the value actually returned by xa_erase(). Because xa_erase() is atomic and multiple invalidation paths can run concurrently, the same cache-held reference could be dropped more than once. This creates a double-put condition that can free an IRQ-related entry while it is still mapped by an ITE, resulting in a use-after-free and memory corruption in host kernel context. Public reporting states the flaw can be triggered entirely from guest-side actions in KVM/arm64 and has been demonstrated as a guest-to-host escape yielding host kernel code execution.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation can break guest/host isolation in affected KVM/arm64 environments. The disclosed proof of concept and reporting indicate that an attacker controlling a guest can leverage the race-induced use-after-free to achieve arbitrary code execution in the host kernel, effectively escaping the VM and executing commands on the host with kernel/root privileges. This creates severe risk for multi-tenant arm64 virtualization deployments, including potential full host compromise and follow-on impact to other workloads hosted on the same system.

Mitigation

If you can’t patch tonight, do this now.

If immediate patching is not possible, reduce exposure by avoiding placement of untrusted tenants or workloads on vulnerable arm64 KVM hosts, especially in multi-tenant cloud environments. Restrict access to affected arm64 KVM infrastructure, monitor for anomalous guest behavior involving GIC/ITS activity or unexplained host instability, and prioritize isolation or shutdown of vulnerable hosts exposed to attacker-controlled guests. There is no complete mitigation equivalent to the patch in the provided content; patching the host kernel is the primary corrective action.

Remediation

Patch, then assume compromise.

Apply the upstream fix for CVE-2026-46316, which changes vgic_its_invalidate_cache() so that it drops the cache reference only for the entry actually removed by xa_erase(), preventing multiple puts of the same cache-held reference during concurrent invalidation. The content identifies the fixing commit as 13031fb6b8357fbbcded2a7f4cba73e4781ee594. Upgrade to a Linux kernel release from your vendor or upstream that includes this patch. The disclosure also recommends applying related follow-up fixes, including commit 70543358fa08e0f7cebc3447c3b70fe97ad7aaa8 and commit f2ca45b50d4216c9cc7ffabf50d9ad1932209251, where applicable.
PUBLIC EXPLOITS

Exploits

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VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

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LinuxLinux Kerneloperating_system

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Threat actor evidence

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Associated malware

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Detection signatures

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