Understanding CVE-2026-31431: The 'Copy Fail' Linux Privilege Escalation Vulnerability
On April 29, 2026, researchers disclosed a critical local privilege escalation vulnerability in the Linux kernel, identified as CVE-2026-31431, commonly referred to as 'Copy Fail'. This flaw allows unprivileged local users to escalate their privileges to root across major Linux distributions released since 2017, including Ubuntu, Red Hat Enterprise Linux, and SUSE. The vulnerability stems from a logic error in the kernel's cryptographic subsystem, specifically within the algif_aead module of the AF_ALG interface, enabling attackers to modify the in-memory cache of privileged executable files without altering the physical files on disk. This issue is particularly concerning in environments such as Kubernetes clusters and multi-tenant hosts, where it can facilitate container escapes and compromise of shared resources. Given the availability of a reliable proof-of-concept exploit and active exploitation in the wild, organizations are urged to apply vendor-issued kernel updates immediately to mitigate the risk.
Kill Chain
