Copy.Fail Linux Vulnerability
Summary
Copy.Fail is a critical Linux kernel vulnerability that lets an attacker with basic user access escalate their privileges to root (the highest permission level) by exploiting the kernel crypto API and splice function (a system call that efficiently moves data between files). The vulnerability affects most Linux distributions without requiring special tricks or version-specific offsets, and it's especially dangerous in shared environments like Kubernetes clusters and cloud servers where multiple users or containers share the same kernel.
Solution / Mitigation
The mainline fix landed on 1 April. Distros are rolling kernels out now. Patch. Additionally, a custom seccomp profile (a security filter that restricts which system calls programs can use) is needed, since Kubernetes Pod Security Standards and the default RuntimeDefault seccomp profile do not block the vulnerable syscall.
Classification
Original source: https://www.schneier.com/blog/archives/2026/05/copy-fail-linux-vulnerability.html
First tracked: May 12, 2026 at 08:00 AM
Classified by LLM (prompt v3) · confidence: 72%