Copyright © 2012 Red Hat, Inc. All rights reserved. Low 2026-08-15T00:00:00 kernel: posix-cpu-timers: Use u64 multiplication in update_rlimit_cpu() 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H CWE-190

In the Linux kernel, the following vulnerability has been resolved: posix-cpu-timers: Use u64 multiplication in update_rlimit_cpu() update_rlimit_cpu() converts the RLIMIT_CPU value to nanoseconds with u64 nsecs = rlim_new * NSEC_PER_SEC; On 32-bit kernels both rlim_new (unsigned long) and NSEC_PER_SEC (1000000000L) are 32-bit, so the multiplication is performed in unsigned long and truncated for rlim_new > 4 seconds before being widened to u64. The same file already casts to u64 for the matching computation in check_process_timers(): u64 softns = (u64)soft * NSEC_PER_SEC; As a result, the truncated value is installed into the CPUCLOCK_PROF expiry cache (nextevt), causing the process CPU timer to be programmed to fire prematurely for any RLIMIT_CPU soft limit >= 5 seconds. The actual SIGXCPU/SIGKILL decision in check_process_timers() already casts to u64 and is therefore correct, so limit enforcement is not broken; only the expiry-cache programming is wrong. Apply the same cast here so both paths convert rlim_cur identically. 64-bit kernels are unaffected.

A flaw was found in the Linux kernel's `posix-cpu-timers` component on 32-bit systems. An integer truncation vulnerability occurs in the `update_rlimit_cpu()` function when converting the `RLIMIT_CPU` value to nanoseconds. This issue causes the process CPU timer to be programmed to fire prematurely for `RLIMIT_CPU` soft limits of 5 seconds or more. While actual resource limit enforcement remains correct, this premature timer expiry could lead to a denial of service for affected processes.

Red Hat Enterprise Linux 10 Fix deferred kernel Red Hat Enterprise Linux 6 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel-rt Red Hat Enterprise Linux 8 Fix deferred kernel Red Hat Enterprise Linux 8 Fix deferred kernel-rt Red Hat Enterprise Linux 9 Fix deferred kernel Red Hat Enterprise Linux 9 Fix deferred kernel-rt https://www.cve.org/CVERecord?id=CVE-2026-72068 https://nvd.nist.gov/vuln/detail/CVE-2026-72068 https://lore.kernel.org/linux-cve-announce/2026081518-CVE-2026-72068-23e7@gregkh/T