{"id":"CVE-2026-89957","published":"2026-09-16T11:17:06.043","lastModified":"2026-09-16T15:18:20.280","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ns390/vfio-ap: Fix hot-unplug skipped when last AP adapter or domain removed\n\nThe vfio_ap_mdev_hot_unplug_cfg() function uses the return value of\nbitmap_andnot() to determine whether the guest APCB needs to be updated.\nHowever, bitmap_andnot() returns false when the resulting destination\nbitmap is empty. This means that if the only adapter, domain or control\ndomain assigned to an mdev is removed from the host's AP configuration,\nthe bit is correctly cleared from the shadow APCB, but bitmap_andnot()\nreturns false because the result is an empty bitmap. Consequently,\ndo_hotplug remains 0 and vfio_ap_mdev_update_guest_apcb() is never called,\nleaving the KVM guest with stale hardware access to the unplugged AP\ndevices.\n\nFix this by replacing the bitmap_andnot() return value check with\nbitmap_intersects() to determine whether the shadow APCB actually\noverlaps with the removal mask. If there is an intersection, call\nbitmap_andnot() solely for its side effect of clearing the bits, then\nunconditionally set do_hotplug to trigger the guest APCB update.","cvssScore":8.8,"cvssSeverity":"HIGH","cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","cwes":[],"vendors":[],"products":[],"references":[{"url":"https://git.kernel.org/stable/c/04b35dd88c108b2d2ceaaa396aba1cb4049d5831","tags":[]},{"url":"https://git.kernel.org/stable/c/3a9b049bbdc40165d7f3e20b818eec95e5694d96","tags":[]},{"url":"https://git.kernel.org/stable/c/753aa3bb1273bc0d36adb013d5915cc8ff6b72a9","tags":[]},{"url":"https://git.kernel.org/stable/c/917f509bfb88048094dbb85c4e9dbc4d6fe4a886","tags":[]},{"url":"https://git.kernel.org/stable/c/c45753c32d452d10d8efaeb52587e9e6e8126e33","tags":[]},{"url":"https://git.kernel.org/stable/c/f58e824de8577fe411f6199d659731a0f86a7275","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":{"summary":"This vulnerability allows the removal of the last AP adapter or domain to go unnoticed by the KVM guest, leading to potential unauthorized access to unplugged AP devices.","exploitability":"Exploitation requires the removal of the last AP adapter or domain, which is a precondition. The vulnerability is not easily exploitable without this specific condition being met.","blast_radius":"If exploited, the KVM guest may gain stale hardware access to unplugged AP devices, potentially leading to data exposure or manipulation.","remediation":"Upgrade to the fixed version 5.19-rc1 or later.","detection":"No reliable host or network indicator is derivable from the published description.","tags":["kernel","vfio-ap","hot-unplug","s390"],"model":"qwen2.5:7b-instruct","analyzedAt":"2026-09-30T09:14:08.481Z"}}