CVE-2026-8933: Local Privilege Escalation in Ubuntu snap-confine | Qualys

Summary: Qualys Threat Research Unit identified CVE-2026-8933, a Local Privilege Escalation flaw in snap-confine that lets an unprivileged local user gain full root access on default installations of Ubuntu Desktop 24.04, 25.10, and 26.04. The flaw stems from Canonical's shift of snap-confine from a set-uid-root binary to a set-capabilities model, which leaves a race window during sandbox setup where temporary files under /tmp remain under the caller's control.
Key Takeaway: The exploit chains two race conditions plus a FUSE mount and a symlink to write a malicious .rules file into /run/udev/rules.d/, forcing systemd-udevd to run arbitrary commands as root - meaning any local user on a default Ubuntu desktop is a root compromise away.

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Topics: Vulnerabilities & Patching
Mentions: CVE-2026-8933
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