New Januscape Linux flaw allows VM escape on Intel, AMD devices

CVE-2026-53359 (Januscape) is a critical Linux kernel vulnerability that has existed undetected for 16 years, underscoring how long-lived flaws can lurk in foundational software. The vulnerability allows an attacker with root access inside a virtual machine to escape the VM boundary and execute arbitrary code on the host, directly threatening multi-tenant cloud environments where multiple customers share the same physical infrastructure. The extended window of exposure amplifies the risk, as the flaw may have been exploitable — or even exploited — long before its discovery. Prompt application of the June 2026 patch is essential, as even a partial proof-of-concept (host kernel panic) in the wild signals active attacker interest.