AI-Assisted Research Finds Linux Kernel Flaw Enabling Root Access and VM Escape
Summary
CVE-2026-74580 affects Linux kernels 4.11 to 7.2-rc4, enabling local users to gain root and, in a specific configuration, guests to attack the host. Fixes are available; restrict vhost device access until patched.
Key points
- The vhost flaw, named Vghost, can let an unprivileged local user read and write kernel memory, bypass KASLR, and gain root.
- In a specific setup using a virtual IOMMU and device-IOTLB mode, an untrusted guest can cause out-of-bounds writes into the host's QEMU process, potentially taking control or crashing it.
- The flaw affects Linux kernels from 4.11 through 7.2-rc4 and is tracked as CVE-2026-74580.
- Stale cached memory mappings result from ring reconfiguration commands that do not clear the cache, allowing access through outdated translations.
- The fix clears the cache when a ring is reconfigured. Install a fixed kernel and reboot; restrict access to /dev/vhost-net and /dev/vhost-vsock until then.
- Red Hat, Amazon Linux, and Oracle Linux have shipped fixes. Ubuntu fixed 22.04; fixes for 24.04 and 26.04 were still in progress as of October 13.
- Tencent Zhuque Lab used its Corvus AI research system to help find the flaw. The article reports no public evidence of exploitation.
Article Details
- Vulnerability Types
- Stale memory-mapping cache translations causing out-of-bounds kernel reads and writes
- Severity
- High; reported scores range from 7.3 to 8.8.
- Affected Versions
- Linux kernels 4.11 up to 7.2-rc4
- Exploitation Status
- not_reported
- Exploit Availability
- public_poc
- Patch Status
- partial
- Workarounds
- Restrict access to /dev/vhost-net and /dev/vhost-vsock; remove world access and limit the owning group to trusted virtualization services.
- For the guest-to-host escape, the article reports no interim workaround; a patched kernel is the only remedy.
MITRE ATT&CK
T1068 · Exploitation for Privilege EscalationA local unprivileged user can exploit the flaw to read and write kernel memory and escalate to root.T1611 · Escape to HostIn the specified virtual IOMMU and device-IOTLB configuration, an untrusted guest can exploit the flaw to write into the host's QEMU process.
CVE
Vendors
Amazonreproduced the full local-user-to-root chain on five distribution kernels: Ubuntu 26.04, RHEL 9.8, Amazon Linux 2023, Microsoft Azure Linux 3.0, and Oracle Linux 10.2. On Ubuntu, the device node was limited toOracleon five distribution kernels: Ubuntu 26.04, RHEL 9.8, Amazon Linux 2023, Microsoft Azure Linux 3.0, and Oracle Linux 10.2. On Ubuntu, the device node was limited to the kvm group, so the starting point there was aRed HatRed Hat, Amazon Linux, and Oracle Linux have shipped fixes. Ubuntu has fixed 22.04 and, as of October 13, still lists its 24.04 and 26.04 kernels as in progress.Ubuntu4.11 up to 7.2-rc4. Tencent reproduced the full local-user-to-root chain on five distribution kernels: Ubuntu 26.04, RHEL 9.8, Amazon Linux 2023, Microsoft Azure Linux 3.0, and Oracle Linux 10.2. On Ubuntu, the
Products
LinuxA flaw in Linux's vhost subsystem lets a local user read and write kernel memory at will and become root across nearly a decade of kernel versions. In one virtualization setup, it lets an untrusted virtual machine writeQEMUan untrusted guest can trigger the same bug and make the host kernel write out of bounds into the host's QEMU process. From there, a guest can overwrite a function pointer in QEMU and take control of where the host