CVE-2026-3888 is a local privilege escalation vulnerability in Ubuntu’s snapd package (CVSS 7.5) rooted in a race condition between snap-confine and systemd-tmpfiles that allows any unprivileged local user to gain full root access; the exploit window opens after approximately 10–30 days post-boot, meaning systems that have been running without reboot are within the active exploitation window. Affected releases include Ubuntu Desktop 24.04 LTS, 25.10, and 26.04 LTS (Dev) running snapd prior to 2.73 (LTS) or 2.74.1/2.75 (other releases). Update snapd immediately via apt, prioritize systems that have been running for 10 or more days without reboot, and review shared-user environments such as developer workstations and jump hosts as elevated-risk until patched.