CVE-2018-12896: Canonical Ubuntu Linux

Medium severity, CVSS 5.5. EPSS: 0.6% chance of exploitation in the next 30 days.

An issue was discovered in the Linux kernel through 4.17.3. An Integer Overflow in kernel/time/posix-timers.c in the POSIX timer code is caused by the way the overrun accounting works. Depending on interval and expiry time values, the overrun can be larger than INT_MAX, but the accounting is int based. This basically makes the accounting values, which are visible to user space via timer_getoverrun(2) and siginfo::si_overrun, random. For example, a local user can cause a denial of service (signed integer overflow) via crafted mmap, futex, timer_create, and timer_settime system calls.

Affected products

• Canonical Ubuntu Linux: version 12.04 only; version 14.04 only; version 16.04 only; version 18.04 only
• Debian Debian Linux: version 8.0 only
• Linux Linux Kernel: up to and including 4.17.3

Published 2018-07-02. Last modified 2026-06-17.