{"answers":{"affected":"","exploited":"There is no known exploitation of CVE-2026-89460 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2026-89460 is a vulnerability in Linux, published on 11 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-89460 and fix it if it is affected.\n\nWhat it is: CVE-2026-89460 is a vulnerability in Linux, published on 11 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.\nExploitation: There is no known exploitation of CVE-2026-89460 in the wild and no public exploit code.\n\nAffected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-89460/ (Markdown: https://insights.sbomify.com/CVE-2026-89460/index.md)","id":"CVE-2026-89460","markdown":"https://insights.sbomify.com/CVE-2026-89460/index.md","name":"CVE-2026-89460","record":{"aliases":["AZL-100547","BELL-CVE-2026-89460","DEBIAN-CVE-2026-89460","GHSA-qv9g-m2j2-jrgj","UBUNTU-CVE-2026-89460"],"analysis":{"component_type":"kernel","fix_type":"patch","impacts":["denial_of_service"],"network_reachable":"adjacent_or_local","non_default_config":false,"product_category":"Linux kernel","requires_auth":"low_privilege","summary":"A local attacker can crash the Linux kernel by triggering a null pointer dereference in the s390 CPU measurement facility during CPU hotplug events.","user_interaction":"not_required","vuln_class":"null_dereference"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Linux","cpe":[],"cvss":{"score":null,"severity":null,"source":null,"vector":null,"version":null},"cwes":[],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\ns390/cpum_cf: Handle CPU hotplug via prepare/dead callbacks\n\nThe command 'perf stat -e cycles -- \u003ccommand\u003e' crashes the kernel\nwhen CPUs are hotplug added during that run.\n\nRoot cause is the allocation of struct cpu_cf_events at first\nevent initialization. The allocation is dynamic and the first\nevent that has task context creates such a structure for\neach online CPU. This is not sufficient. CPUs may be offline\nduring event creation and can be set online during the\nperf run time. For example commands\n\n # echo 0 \u003e /sys/devices/system/cpu/cpu1/online\n # perf stat -e cycles -i -- stress-ng -t10s --matrix X\n # sleep 1\n # echo 1 \u003e /sys/devices/system/cpu/cpu1/online\n\ncreate an event for CPUs 0,2-X. Since the events are created with\ntask-context, the scheduler will eventually schedule the program\non CPU1. This CPU has not created and initialized any per\nCPU event infrastructure as that CPU was not online at the time\nof the perf invocation. Thus when the scheduler runs stress-ng\non CPU1, the function cpumf_pmu_add() refers to a NULL pointer:\n\n struct cpu_cf_events *cpuhw = this_cpu_cfhw();\n\nThis function call is invoked after the task stress-ng has been\nmade runnable on CPU1. And this_cpu_cfhw() returns NULL.\n\nThe result is a panic:\nUnable to handle kernel pointer dereference in virtual kernel address space\nFailing address: 0000000000000000 TEID: 0000000000000483\n....\nKrnl PSW : 0404d00180000000 000003ef8291fd0c (cpumf_pmu_add+0x3c/0x80)\n....\nCall Trace:\n [\u003c000003ef8291fd0c\u003e] cpumf_pmu_add+0x3c/0x80\n [\u003c000003ef82bb5e3e\u003e] event_sched_in+0xae/0x190\n [\u003c000003ef82bb60d6\u003e] merge_sched_in+0x1b6/0x390\n [\u003c000003ef82bb65b8\u003e] visit_groups_merge.constprop.0.isra.0+0x308/0x5b0\n [\u003c000003ef82bb689a\u003e] pmu_groups_sched_in+0x3a/0x50\n [\u003c000003ef82bb6a30\u003e] ctx_sched_in+0x180/0x260\n [\u003c000003ef82bb780c\u003e] perf_event_context_sched_in+0x11c/0x2d0\n [\u003c000003ef82bb79ee\u003e] __perf_event_task_sched_in+0x2e/0xc0\n [\u003c000003ef82994834\u003e] finish_task_switch.isra.0+0x1a4/0x250\n....\nLast Breaking-Event-Address:\n [\u003c000003ef8291f1d8\u003e] this_cpu_cfhw+0x38/0x40\n\nThe issue arises only in per-task context when the CPUMF facility is\nused and the scheduler picks a random CPU for such a process to run on.\nThe scheduler enables the CPUMF infrastructure via PMU callback\nfunctions pmu::add() and pmu::del().\n\nIntroduce a CPU hotplug prepare/dead callback pair which creates and\nremoves the per CPU counter data while the CPU is offline. Count the\nusers which track every CPU (cpu == -1), that is perf_event_open()\nevents with task context and /dev/hwctr device sessions, in the new\ncounter cpu_cf_root::tskcnt, protected by pmc_reserve_mutex.\nThis ensures the infrastructure is available when\nnew CPU is selected to run the per-task context process.\n\nIn cpum_cf_free_root() and cpum_cf_free_cpu() ensure the reference\npointer to data structures is set to NULL before the data is freed\nto prevent interrupt handlers to access stale data.\n\n[gor@linux.ibm.com: change commit message]","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":true,"headline":"s390/cpum_cf: Handle CPU hotplug via prepare/dead callbacks","id":"CVE-2026-89460","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":null,"products":[],"type":"null_dereference","year":"2026"},"n_packages":0,"n_references":5,"next":{"headline":"power: supply: max17040: synchronize work cancellation on suspend","id":"CVE-2026-89461"},"packages":[],"prev":{"headline":"s390/percpu: Fix MVIY_PERCPU() with older binutils","id":"CVE-2026-89459"},"products":["Linux"],"published":"2026-09-11","related":[],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"}],"ssvc":{"automatable":null,"exploitation":null,"technical_impact":null},"state":"PUBLISHED","updated":"2026-10-19","vendors":["Linux"]},"summary":"A local attacker can crash the Linux kernel by triggering a null pointer dereference in the s390 CPU measurement facility during CPU hotplug events.","url":"https://insights.sbomify.com/CVE-2026-89460/"}