Security researcher claims to they found KVM guest-host escape flaw
Firecracker MicroVMs, which started at AWS, seem to be the problem
Security researcher Paulos Yibelo claims to have discovered a critical vulnerability in Linux KVM, a hypervisor commonly used in large-scale cloud computing. Yibelo shared the news on X, revealing he won a bug bounty award for finding a "Full VM escape zeroday" that grants guest host root privileges within industry-standard hypervisors.
The vulnerability was identified while testing Vercel's MicroVM sandbox, which utilizes Firecracker MicroVMs developed by AWS and relies on Linux KVM. Vercel CEO Guillermo Rauch confirmed the bug, emphasizing that the flaw impacts the industry's leading Linux virtualization solution. The Register has not found any further details from Rauch or Yibelo on relevant mailing lists.
Guest-host escapes are particularly concerning, as they allow an attacker to take control of an entire server and potentially other guest VMs. KVM is widely used by major cloud providers like AWS and Google, as well as enterprise virtualization companies such as Nutanix, HPE, and Proxmox. Open-source Firecracker, which could be deployed in various systems, also relies on KVM.
Responsible disclosure is crucial to prevent potential damage. Once a fix is available, implementing it may require minimal disruption or downtime, as hot-patching KVM and migrating live VMs to patched hosts are possible solutions. This vulnerability may be the second significant flaw discovered in KVM this year, following the Januscape flaw.
Experts suggest Yibelo's reward should exceed the $50,000 offered by Vercel's bug bounty program due to the bug's severity.
Written by urgent.news from The Register's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
