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CVE-2026-89775 is a guest-to-host escape vulnerability in Linux KVM on ARM64 systems with nested virtualization enabled. A stage-1 page-table walk-level truncation can cause a range-size calculation to return zero; VNCR pseudo-TLB invalidation then skips invalidation, potentially leaving a freed host page mapped and writable at a fixed host-kernel address. A malicious guest can obtain 64-bit read/write access to host kernel memory and may be able to execute code on the host.
The issue affects multi-tenant ARM64 cloud deployments that expose nested-virtualization-capable instances and local systems where unprivileged users can access /dev/kvm. Nested virtualization is experimental, disabled by default, and requires Armv8.4 FEAT_NV2 hardware, limiting exposure. Upstream fixed the flaw in commit 8053393680d4; fixes are available in Linux 6.18.51, 7.2.5, and 7.3-rc1. No public exploit or active exploitation had been reported.
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3 events from the most recent confirmed update back to the earliest known activity.
The affected upstream Linux kernel code was introduced in commit 7270cc9157f47, establishing the code path later identified as vulnerable to missed pseudo-TLB invalidation under nested virtualization.
Researcher Hyunwoo Kim disclosed CVE-2026-89775, a KVM/arm64 nested-virtualization flaw that can skip required TLB invalidation and leave freed host memory mapped writable to a guest. The issue could permit 64-bit guest reads and writes to host kernel memory and potentially enable guest-to-host escape.
Linux mainline incorporated commit 8053393680d4 to fix the KVM/arm64 nested-virtualization flaw. Upstream fixes were subsequently available in Linux 6.18.51, 7.2.5, and 7.3-rc1.
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A newly disclosed KVM/x86 vulnerability, **CVE-2026-64561** or **Zapscape**, allows a privileged L1 guest to break nested virtualization isolation and achieve guest-to-host escape on Linux systems. The bug is a use-after-free in KVM/x86 shadow MMU emulation tied to the recursive shadow-page zap path and stale-root check ordering during guest-triggered page fault handling, enabling corruption of host kernel shadow pages and potential host code execution. Researcher **Hyunwoo Kim** reported the flaw to the Linux kernel security team and published a proof-of-concept showing creation of a root-owned file on the host. The issue affects both **Intel** and **AMD** hosts and is especially serious for environments that run untrusted guests with nested virtualization enabled, including multi-tenant public cloud infrastructure. On Intel, exploitation requires exposing both EPT page walk lengths 4 and 5 to the L1 guest, while no equivalent constraint was noted for AMD. The vulnerability affects Linux KVM versions from **5.9 onward** across the disclosed commit range, and a fix has been merged upstream into mainline Linux, with users advised to deploy patched stable kernels or vendor-backported updates; no in-the-wild exploitation has been claimed.
Aug 7, 2026
A critical guest-to-host escape vulnerability in KVM on **arm64** systems, tracked as **`CVE-2026-46316`** and dubbed **ITScape**, was publicly disclosed with working proof-of-concept exploit code. Researcher **Hyunwoo Kim** reported that the flaw resides in the in-kernel **vGIC-ITS** implementation, where a race condition and double-put use-after-free in `vgic_its_invalidate_cache()` can be triggered entirely from an untrusted guest VM, allowing execution of commands on the host with **kernel privileges**. The issue affects arm64 Linux kernels spanning builds from late April 2024 through early June 2026 and raises particular concern for **multi-tenant public cloud** environments running unpatched arm64 KVM hosts. The published PoC reportedly demonstrates host-kernel code execution on `aarch64`, including creation of a root-owned `/ITScape` file on the host, while Linux kernel maintainers have already merged a fix that changes `vgic_put_irq()` handling based on the return value of `xa_erase()`. The disclosure also advises applying additional related patches, including one addressing **`CVE-2026-46317`**.
Jun 29, 2026
**CVE-2022-1852** is a moderate-severity NULL-pointer dereference in the Linux kernel's x86 KVM instruction-emulation path. A low-privileged attacker in an Intel-based virtual-machine guest can execute an illegal instruction and trigger a fault in `x86_emulate_insn`, causing a denial of service. Red Hat assigned a CVSS v3.1 score of 5.5 and classified the defect as CWE-476. The upstream Linux fix, commit `fee060cd52d69c114b62d1a2948ea9648b5131f9`, prevents KVM from invoking the x86 emulator before an instruction has been decoded, avoiding use of stale emulation context after breakpoint-related handling. Red Hat released corrected kernel packages for affected RHEL 8 and RHEL 9 systems and related products; RHEL 6 and 7 kernels are not affected. Where patching cannot be performed promptly, Red Hat recommends blacklisting the affected KVM kernel module at boot to prevent it from loading.
Aug 26, 2026