{"id":"CVE-2026-93181","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nperf/x86/intel/uncore: Fix uncore_box ref/unref ordering\n\nIn uncore_event_cpu_online(), uncore_box_ref() was called before\nuncore_change_context()","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nperf/x86/intel/uncore: Fix uncore_box ref/unref ordering\n\nIn uncore_event_cpu_online(), uncore_box_ref() was called before\nuncore_change_context().  uncore_box_ref() ga…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= c74443d92f68f07c03ae242ced554b749e6c6736 < 64aa1bb4017d598828c6d8cd718f43daf2a83375","Linux >= c74443d92f68f07c03ae242ced554b749e6c6736 < 174f0582e38abe03b88e15f04bfe58490f88cb19","Linux 6.11"],"published":"2026-09-17","updated":"2026-09-17","sourceUpdated":"2026-09-17T17:18:14.027","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-93181","references":[{"url":"https://git.kernel.org/stable/c/174f0582e38abe03b88e15f04bfe58490f88cb19","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/64aa1bb4017d598828c6d8cd718f43daf2a83375","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd","cve.org"],"ingestedAt":"2026-09-17T16:21:47.727Z","epss":0.00189,"epssPercentile":0.08815,"slug":"CVE-2026-93181","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nperf/x86/intel/uncore: Fix uncore_box ref/unref ordering\n\nIn uncore_event_cpu_online(), uncore_box_ref() was called before\nuncore_change_context().  uncore_box_ref() gates on box->cpu >= 0,\nbut box->cpu is still -1 at that point because uncore_change_context()\nhas not run yet.  As a result, the box is never initialized on the\nfirst CPU to come online in a die, leaving it permanently\nuninitialized in the single-CPU-per-die case.\n\nThus, box->refcnt is one count below the true value, and in the CPU\noffline path, the box will be torn down on the second-to-last CPU.\n\nIn uncore_event_cpu_offline(), uncore_box_unref() was called after\nuncore_change_context(), so box->cpu is already -1 when the collector\nCPU goes offline, which prevents it from tearing down the box.\n\nFix by swapping the call order in both paths so that\nuncore_box_{ref,unref}() runs at the point where box->cpu reflects\nthe correct context.\n\nMove allocate_boxes() out of uncore_box_ref() to enable this\nreordering.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}