{"id":"CVE-2026-89756","title":"kernel: mm/migrate: report RCU-tasks quiescent states in migrate_pages_batch() (CVE-2026-89756)","summary":"A flaw was found in the Linux kernel. When performing memory migration on KVM (Kernel-based Virtual Machine) hosts, the `migrate_pages_batch()` function fails to report RCU (Read-Copy Update) tasks quiescent states during large batch unmap…","severity":"medium","cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cvssSource":"vendor","cwe":"CWE-821","vendor":"Red Hat","product":"Red Hat Enterprise Linux 9","affected":["enterprise_linux 10","enterprise_linux 6","enterprise_linux 8","enterprise_linux 9","openshift_container_platform 4"],"published":"2026-09-11","updated":"2026-09-15","sourceUpdated":"2026-09-15T19:56:02+00:00","source":"CSAF","sourceUrl":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89756.json","references":[{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89756.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89756"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532146"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89756"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89756"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89756.mbox"},{"url":"https://git.kernel.org/stable/c/4996a7bc01ef35570664854dac2530c604981039"},{"url":"https://git.kernel.org/stable/c/5dc0daff0341c6baba19c38f47d299ac831d7e99"},{"url":"https://git.kernel.org/stable/c/66734981b4d3c105223a13c827c9c73be18d91ad"},{"url":"https://git.kernel.org/stable/c/efe8f86c0916f0f74eea74ae21a3b37f728c6bad"},{"url":"https://git.kernel.org/stable/c/8c6d63d434ebb85c6cf3dac1e70a171b183c6614"},{"url":"https://git.kernel.org/stable/c/4757542649af56d894e25e30f57cd497dffad53f"}],"tags":["csaf","vex","red-hat","cve.org"],"epss":0.00191,"epssPercentile":0.09072,"ingestedAt":"2026-09-14T15:23:07.448Z","slug":"CVE-2026-89756","body":"## Overview\n\nA flaw was found in the Linux kernel. When performing memory migration on KVM (Kernel-based Virtual Machine) hosts, the `migrate_pages_batch()` function fails to report RCU (Read-Copy Update) tasks quiescent states during large batch unmapping operations. This oversight causes the migrating task to become an RCU holdout, leading to a prolonged stall in the RCU grace period. This can result in a Denial of Service (DoS) by keeping the CPU busy for an extended duration.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, … · updated 2026-09-15 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89756.json)\n\n**kernel: mm/migrate: report RCU-tasks quiescent states in migrate_pages_batch()** — rated Moderate by Red Hat. Released 2026-09-11, updated 2026-09-15.\n\nAffected:\n\n- Red Hat Enterprise Linux 10\n- Red Hat Enterprise Linux 6\n- Red Hat Enterprise Linux 8\n- Red Hat Enterprise Linux 9\n- Red Hat OpenShift Container Platform 4\n\nNo fix planned:\n\n- Red Hat Enterprise Linux 6\n- Red Hat Enterprise Linux 10\n- Red Hat Enterprise Linux 8\n- Red Hat Enterprise Linux 9\n- Red Hat OpenShift Container Platform 4\n\nNot affected:\n\n- Red Hat Enterprise Linux 7\n\n## Remediation\n\nOut of support scope","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":205522,"id":"CVE-2026-89756","ts":1789576723233,"field":"cvss","old":"4.7","new":"5.5"},{"seq":204079,"id":"CVE-2026-89756","ts":1789490231348,"field":"cvss","old":null,"new":"4.7"},{"seq":204078,"id":"CVE-2026-89756","ts":1789490231348,"field":"severity","old":"none","new":"medium"},{"seq":147674,"id":"CVE-2026-89756","ts":1789270211834,"field":"cvss","old":null,"new":"4.7"},{"seq":147673,"id":"CVE-2026-89756","ts":1789270211834,"field":"severity","old":"none","new":"medium"},{"seq":109422,"id":"CVE-2026-89756","ts":1789183731852,"field":"cvss","old":null,"new":"4.7"},{"seq":109421,"id":"CVE-2026-89756","ts":1789183731852,"field":"severity","old":"none","new":"medium"}]}