AI-Found Linux Kernel Flaw Gives Local Users Root, and Can Break a Guest Out to the Host

Security researchers at Tencent's Zhuque Lab, using their Corvus AI-assisted analysis pipeline, uncovered a nearly decade-old Linux kernel bug in the vhost subsystem, tracked as CVE-2026-74580 and dubbed Vghost. The flaw lets a local user who can open /dev/vhost-net or /dev/vhost-vsock read and write arbitrary kernel memory, bypass KASLR, and escalate to root, and in a second scenario involving virtio behind a virtual IOMMU with device-IOTLB mode, lets a malicious guest VM corrupt the host's QEMU process memory and potentially hijack its execution. The root cause is a stale address-translation cache that isn't invalidated when ring addresses or size are changed via VHOST_SET_VRING_ADDR or VHOST_SET_VRING_NUM while a queue is active, a gap introduced by kernel changes from 2017 and 2020. Affected kernels range from 4.11 through 7.2-rc4, with confirmed exploitation on Ubuntu, RHEL, Amazon Linux, Microsoft Azure Linux, and Oracle Linux; a fix (commit de845981da67) has landed upstream and in several vendor kernels, and administrators should update immediately or restrict access to the vhost device nodes in the meantime.