{"id":"CVE-2026-45919","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-45919","generatedAt":"2026-10-28T04:32:46.223Z","title":"In the Linux kernel, the following vulnerability has been resolved: sched/rt: Skip currently executing CPU in rto_next_cpu() CPU0 becomes overloaded when hosting a CPU-bound RT task, a non-CPU-bound RT task, and a CFS task stuck in kernel space.","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsched/rt: Skip currently executing CPU in rto_next_cpu()\n\nCPU0 becomes overloaded when hosting a CPU-bound RT task, a non-CPU-bound\nRT task, and a CFS task stuck in kernel space. When other CPUs switch from\nRT to non-RT tasks, RT load balancing (LB) is triggered; with\nHAVE_RT_PUSH_IPI enabled, they send IPIs to CPU0 to drive the execution\nof rto_push_irq_work_func. During push_rt_task on CPU0,\nif next_task->prio < rq->donor->prio, resched_curr() sets NEED_RESCHED\nand after the push operation completes, CPU0 calls rto_next_cpu().\nSince only CPU0 is overloaded in this scenario, rto_next_cpu() should\nideally return -1 (no further IPI needed).\n\nHowever, multiple CPUs invoking tell_cpu_to_push() during LB increments\nrd->rto_loop_next. Even when rd->rto_cpu is set to -1, the mismatch between\nrd->rto_loop and rd->rto_loop_next forces rto_next_cpu() to restart its\nsearch from -1. With CPU0 remaining overloaded (satisfying rt_nr_migratory\n&& rt_nr_total > 1), it gets reselected, causing CPU0 to queue irq_work to\nitself and send self-IPIs repeatedly. As long as CPU0 stays overloaded and\nother CPUs run pull_rt_tasks(), it falls into an infinite self-IPI loop,\nwhich triggers a CPU hardlockup due to continuous self-interrupts.\n\nThe trigging scenario is as follows:\n\n         cpu0                      cpu1                    cpu2\n                                pull_rt_task\n                              tell_cpu_to_push\n                 <------------irq_work_queue_on\nrto_push_irq_work_func\n       push_rt_task\n    resched_curr(rq)                                   pull_rt_task\n    rto_next_cpu                                     tell_cpu_to_push\n                      <-------------------------- atomic_inc(rto_loop_next)\nrd->rto_loop != next\n     rto_next_cpu\n   irq_work_queue_on\nrto_push_irq_work_func\n\nFix redundant self-IPI by filtering the initiating CPU in rto_next_cpu().\nThis solution has been verified to effectively eliminate spurious self-IPIs\nand prevent CPU hardlockup scenarios.","published":"2026-05-27T14:17:07.000Z","lastModified":"2026-06-24T17:22:39.000Z","status":"Undergoing Analysis","sourceIdentifier":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","cvss":{"version":"3.1","score":5.5,"severity":"MEDIUM","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"},"cwe":["CWE-835"],"affected":["linux/linux kernel"],"epss":{"score":0.0013,"percentile":0.02648,"date":"2026-10-27","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (0.13%). Track it; it rarely justifies an emergency change on its own."},"changes":[],"references":[{"url":"https://git.kernel.org/stable/c/16ca9f3117e9a294646c897daf08a5ab546c711b","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/3b3c672a66db3de3b40f8a7057864bc1f874ede3","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/52aeb1e07ec223caf212f036817976c98d2aa250","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/8ad5577b2d4acfd83f03d97a0aece2d18aac5f07","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/94894c9c477e53bcea052e075c53f89df3d2a33e","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/9f25edc5a20cb52a5abbf25f0724bb4732b81801","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/a6a73403733e86748421f2eeaf028c85683ef896","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/d57d0746276a88ea43a2cc62b849fd8a95e32e41","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-45919","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}