New Linux 'Copy Fail' Vulnerability Enables Root Access on Major Distributions
Apr 30, 2026
Linux / Vulnerability
Cybersecurity researchers have disclosed details of a Linux local privilege escalation (LPE) flaw that could allow an unprivileged local user to obtain root. The high-severity vulnerability tracked as CVE-2026-31431 (CVSS score: 7.8) has been codenamed Copy Fail by Xint.io and Theori. "An unprivileged local user can write four controlled bytes into the page cache of any readable file on a Linux system, and use that to gain root," the vulnerability research team at Xint.io and Theori said . At its core, the vulnerability stems from a logic flaw in the Linux kernel's cryptographic subsystem, specifically within the algif_aead module. The issue was introduced in a source code commit made in August 2017. Successful exploitation of the shortcoming could allow a simple 732-byte Python script to edit a setuid binary and obtain root on essentially all Linux distributions shipped since 2017, including Amazon Linux, RHEL, SUSE, and Ubuntu. The Python exploit involves four ...