{"id":"CVE-2026-72068","summary":"posix-cpu-timers: Use u64 multiplication in update_rlimit_cpu()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nposix-cpu-timers: Use u64 multiplication in update_rlimit_cpu()\n\nupdate_rlimit_cpu() converts the RLIMIT_CPU value to nanoseconds with\n\n        u64 nsecs = rlim_new * NSEC_PER_SEC;\n\nOn 32-bit kernels both rlim_new (unsigned long) and NSEC_PER_SEC\n(1000000000L) are 32-bit, so the multiplication is performed in unsigned\nlong and truncated for rlim_new \u003e 4 seconds before being widened to u64.\n\nThe same file already casts to u64 for the matching computation in\ncheck_process_timers():\n\n        u64 softns = (u64)soft * NSEC_PER_SEC;\n\nAs a result, the truncated value is installed into the CPUCLOCK_PROF\nexpiry cache (nextevt), causing the process CPU timer to be programmed\nto fire prematurely for any RLIMIT_CPU soft limit \u003e= 5 seconds. The\nactual SIGXCPU/SIGKILL decision in check_process_timers() already casts\nto u64 and is therefore correct, so limit enforcement is not broken;\nonly the expiry-cache programming is wrong. Apply the same cast here so\nboth paths convert rlim_cur identically.\n\n64-bit kernels are unaffected.","modified":"2026-08-18T03:30:54.814091706Z","published":"2026-08-15T05:52:21.007Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72068.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/1fafc4d9b411645eb34de43362b966dc8fb3e263"},{"type":"WEB","url":"https://git.kernel.org/stable/c/26aff38fefb1d6cd87e22525f41cc8f1aa61b24f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/384628d6cdde0fcd76868606fad3ad8293100afb"},{"type":"WEB","url":"https://git.kernel.org/stable/c/571e1f10b5996ba3e4dc63ea77de4aa309c384ce"},{"type":"WEB","url":"https://git.kernel.org/stable/c/cff8281bacd2866767e6194c3079d33b6c5a74f4"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ea6a188ee805e841a0e242f14d15953e0dfa74bb"},{"type":"WEB","url":"https://git.kernel.org/stable/c/edf6babb9edd2d3e19229ade339081f439d4f478"},{"type":"WEB","url":"https://git.kernel.org/stable/c/feb5c87c8514444ba891b75a5a3eae57c64edaf8"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72068.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-72068"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"858cf3a8c59968e7c5f7c1a1192459a0d52d1ab4"},{"fixed":"feb5c87c8514444ba891b75a5a3eae57c64edaf8"},{"fixed":"384628d6cdde0fcd76868606fad3ad8293100afb"},{"fixed":"1fafc4d9b411645eb34de43362b966dc8fb3e263"},{"fixed":"cff8281bacd2866767e6194c3079d33b6c5a74f4"},{"fixed":"edf6babb9edd2d3e19229ade339081f439d4f478"},{"fixed":"ea6a188ee805e841a0e242f14d15953e0dfa74bb"},{"fixed":"571e1f10b5996ba3e4dc63ea77de4aa309c384ce"},{"fixed":"26aff38fefb1d6cd87e22525f41cc8f1aa61b24f"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-72068.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.11.0"},{"fixed":"5.10.261"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.212"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.178"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.145"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.97"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.40"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.5"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-72068.json"}}],"schema_version":"1.9.0"}