{"api_version":"1","generated_at":"2026-09-17T23:44:45+00:00","cve":"CVE-2026-89777","urls":{"html":"https://cve.report/CVE-2026-89777","api":"https://cve.report/api/cve/CVE-2026-89777.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-89777","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-89777"},"summary":{"title":"vfio/pci: clear vdev->msi_perm after freeing it on init failure","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nvfio/pci: clear vdev->msi_perm after freeing it on init failure\n\nvfio_msi_cap_len() lazily allocates the per-device MSI permission table:\n\n\tvdev->msi_perm = kmalloc_obj(struct perm_bits, GFP_KERNEL_ACCOUNT);\n\tif (!vdev->msi_perm)\n\t\treturn -ENOMEM;\n\n\tret = init_pci_cap_msi_perm(vdev->msi_perm, len, flags);\n\tif (ret) {\n\t\tkfree(vdev->msi_perm);\n\t\treturn ret;\t\t/* vdev->msi_perm left dangling */\n\t}\n\nWhen init_pci_cap_msi_perm() -> alloc_perm_bits() fails with -ENOMEM, the\nerror path frees vdev->msi_perm but leaves the freed pointer stored in\nit. vdev->msi_perm is not re-zeroed later because struct\nvfio_pci_core_device is per-device and persists across open/close cycles,\nand the vfio_config_init() error path returns without calling\nvfio_config_free(). So the dangling pointer outlives the failed open.\n\nThat leads to two use-after-frees on the same device:\n\n1. Reuse. The next vfio_config_init() sees the stale pointer at\n   \"if (vdev->msi_perm) return len;\" and reuses the freed object. MSI\n   config accesses in vfio_pci_config_rw_single() then dereference and\n   call the freed perm->readfn / perm->writefn function pointers.\n\n2. Double free. A later vfio_config_free() runs free_perm_bits() and\n   kfree() on the already-freed object.\n\nFix it by NULLing vdev->msi_perm after the kfree(), matching the\nNULL-after-free discipline already used in free_perm_bits() and\nvfio_config_free().\n\n  BUG: KASAN: slab-use-after-free in vfio_pci_config_rw_single (drivers/vfio/pci/vfio_pci_config.c:1961)\n  Read of size 8 at addr ffff88800fcc88d0 by task exploit/143\n  Call Trace:\n   ...\n   kasan_report (mm/kasan/report.c:595)\n   vfio_pci_config_rw_single (drivers/vfio/pci/vfio_pci_config.c:1961)\n   vfio_pci_config_rw (drivers/vfio/pci/vfio_pci_config.c:1986)\n   vfio_pci_rw (drivers/vfio/pci/vfio_pci_core.c:1599)\n   vfs_read (fs/read_write.c:572)\n   __x64_sys_pread64 (fs/read_write.c:764)\n   do_syscall_64 (arch/x86/entry/syscall_64.c:94)\n   ...\n\nFollowed on device close by a double free of the same object:\n\n  Oops: general protection fault, probably for non-canonical address\n    0x1f63e0e8000008: 0000 [#1] SMP KASAN NOPTI\n  RIP: 0010:kfree (mm/slub.c:6711)\n  Call Trace:\n   vfio_config_free (drivers/vfio/pci/vfio_pci_config.c:1861)\n   vfio_pci_core_disable (drivers/vfio/pci/vfio_pci_core.c:685)\n   vfio_pci_core_close_device (drivers/vfio/pci/vfio_pci_core.c:777)\n   vfio_df_close (drivers/vfio/vfio_main.c:602)\n   vfio_device_fops_release (drivers/vfio/vfio_main.c:648)\n   __fput (fs/file_table.c:512)\n   __x64_sys_close (fs/open.c:1496)\n   do_syscall_64 (arch/x86/entry/syscall_64.c:94)\n   ...\n  Kernel panic - not syncing: Fatal exception","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-16 09:17:08","updated_at":"2026-09-16 15:18:06"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"8.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","baseScore":8.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"CHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"8.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","data":{"baseScore":8.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/25cdd2a492d868cff1e519a60fe282909c52d385","name":"https://git.kernel.org/stable/c/25cdd2a492d868cff1e519a60fe282909c52d385","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/fda8fb7e8179561693a786a7af593f6b944a21c1","name":"https://git.kernel.org/stable/c/fda8fb7e8179561693a786a7af593f6b944a21c1","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/d665a1688af7f8fefd7c0eb04f2a37122ce007f4","name":"https://git.kernel.org/stable/c/d665a1688af7f8fefd7c0eb04f2a37122ce007f4","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/533d0c5feef85ee6404b9f41d5564fac6971a008","name":"https://git.kernel.org/stable/c/533d0c5feef85ee6404b9f41d5564fac6971a008","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/812f1db7f0755a19ef16ecdc5cec51bcabc5eda5","name":"https://git.kernel.org/stable/c/812f1db7f0755a19ef16ecdc5cec51bcabc5eda5","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/dc77acfeb979dded39b247b60fef0399536bfa77","name":"https://git.kernel.org/stable/c/dc77acfeb979dded39b247b60fef0399536bfa77","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/f0eea8f9013676b42289ec35941e848b8a543e19","name":"https://git.kernel.org/stable/c/f0eea8f9013676b42289ec35941e848b8a543e19","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/eb84cd81040e58dd05ac190f561f2115e3367249","name":"https://git.kernel.org/stable/c/eb84cd81040e58dd05ac190f561f2115e3367249","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89777","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89777","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 30ea32ab1951c80c6113f300fce2c70cd12659e4 eb84cd81040e58dd05ac190f561f2115e3367249 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 30ea32ab1951c80c6113f300fce2c70cd12659e4 f0eea8f9013676b42289ec35941e848b8a543e19 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 30ea32ab1951c80c6113f300fce2c70cd12659e4 d665a1688af7f8fefd7c0eb04f2a37122ce007f4 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 30ea32ab1951c80c6113f300fce2c70cd12659e4 25cdd2a492d868cff1e519a60fe282909c52d385 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 30ea32ab1951c80c6113f300fce2c70cd12659e4 812f1db7f0755a19ef16ecdc5cec51bcabc5eda5 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 30ea32ab1951c80c6113f300fce2c70cd12659e4 533d0c5feef85ee6404b9f41d5564fac6971a008 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 30ea32ab1951c80c6113f300fce2c70cd12659e4 fda8fb7e8179561693a786a7af593f6b944a21c1 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 30ea32ab1951c80c6113f300fce2c70cd12659e4 dc77acfeb979dded39b247b60fef0399536bfa77 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected ac370e3d1f3b01519d2705cd5815d1c9d0a8812b git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected be363e27ec3c3a99793da2be6c07eafb95709c6b git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected f1b10ba5739440ca51d66f0b2949cead88d2dd02 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected dde3433de9a067a33d67d65b9093cad3e043e49e git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.4.203 4.5 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.9.203 4.10 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.14.155 4.15 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.19.85 4.20 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.20","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 4.20 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.10.270 5.10.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.15.221 5.15.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.1.188 6.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.157 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.110 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.52 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.6 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"89777","cve":"CVE-2026-89777","epss":"0.002100000","percentile":"0.114460000","score_date":"2026-09-16","updated_at":"2026-09-17 00:07:17"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["drivers/vfio/pci/vfio_pci_config.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"eb84cd81040e58dd05ac190f561f2115e3367249","status":"affected","version":"30ea32ab1951c80c6113f300fce2c70cd12659e4","versionType":"git"},{"lessThan":"f0eea8f9013676b42289ec35941e848b8a543e19","status":"affected","version":"30ea32ab1951c80c6113f300fce2c70cd12659e4","versionType":"git"},{"lessThan":"d665a1688af7f8fefd7c0eb04f2a37122ce007f4","status":"affected","version":"30ea32ab1951c80c6113f300fce2c70cd12659e4","versionType":"git"},{"lessThan":"25cdd2a492d868cff1e519a60fe282909c52d385","status":"affected","version":"30ea32ab1951c80c6113f300fce2c70cd12659e4","versionType":"git"},{"lessThan":"812f1db7f0755a19ef16ecdc5cec51bcabc5eda5","status":"affected","version":"30ea32ab1951c80c6113f300fce2c70cd12659e4","versionType":"git"},{"lessThan":"533d0c5feef85ee6404b9f41d5564fac6971a008","status":"affected","version":"30ea32ab1951c80c6113f300fce2c70cd12659e4","versionType":"git"},{"lessThan":"fda8fb7e8179561693a786a7af593f6b944a21c1","status":"affected","version":"30ea32ab1951c80c6113f300fce2c70cd12659e4","versionType":"git"},{"lessThan":"dc77acfeb979dded39b247b60fef0399536bfa77","status":"affected","version":"30ea32ab1951c80c6113f300fce2c70cd12659e4","versionType":"git"},{"status":"affected","version":"ac370e3d1f3b01519d2705cd5815d1c9d0a8812b","versionType":"git"},{"status":"affected","version":"be363e27ec3c3a99793da2be6c07eafb95709c6b","versionType":"git"},{"status":"affected","version":"f1b10ba5739440ca51d66f0b2949cead88d2dd02","versionType":"git"},{"status":"affected","version":"dde3433de9a067a33d67d65b9093cad3e043e49e","versionType":"git"},{"lessThan":"4.5","status":"affected","version":"4.4.203","versionType":"semver"},{"lessThan":"4.10","status":"affected","version":"4.9.203","versionType":"semver"},{"lessThan":"4.15","status":"affected","version":"4.14.155","versionType":"semver"},{"lessThan":"4.20","status":"affected","version":"4.19.85","versionType":"semver"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["drivers/vfio/pci/vfio_pci_config.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"4.20"},{"lessThan":"4.20","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"5.10.*","status":"unaffected","version":"5.10.270","versionType":"semver"},{"lessThanOrEqual":"5.15.*","status":"unaffected","version":"5.15.221","versionType":"semver"},{"lessThanOrEqual":"6.1.*","status":"unaffected","version":"6.1.188","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.157","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.110","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.52","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.6","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.10.270","versionStartIncluding":"4.20","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.15.221","versionStartIncluding":"4.20","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.1.188","versionStartIncluding":"4.20","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.157","versionStartIncluding":"4.20","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.110","versionStartIncluding":"4.20","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.52","versionStartIncluding":"4.20","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.6","versionStartIncluding":"4.20","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"4.20","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.4.203","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9.203","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14.155","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19.85","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nvfio/pci: clear vdev->msi_perm after freeing it on init failure\n\nvfio_msi_cap_len() lazily allocates the per-device MSI permission table:\n\n\tvdev->msi_perm = kmalloc_obj(struct perm_bits, GFP_KERNEL_ACCOUNT);\n\tif (!vdev->msi_perm)\n\t\treturn -ENOMEM;\n\n\tret = init_pci_cap_msi_perm(vdev->msi_perm, len, flags);\n\tif (ret) {\n\t\tkfree(vdev->msi_perm);\n\t\treturn ret;\t\t/* vdev->msi_perm left dangling */\n\t}\n\nWhen init_pci_cap_msi_perm() -> alloc_perm_bits() fails with -ENOMEM, the\nerror path frees vdev->msi_perm but leaves the freed pointer stored in\nit. vdev->msi_perm is not re-zeroed later because struct\nvfio_pci_core_device is per-device and persists across open/close cycles,\nand the vfio_config_init() error path returns without calling\nvfio_config_free(). So the dangling pointer outlives the failed open.\n\nThat leads to two use-after-frees on the same device:\n\n1. Reuse. The next vfio_config_init() sees the stale pointer at\n   \"if (vdev->msi_perm) return len;\" and reuses the freed object. MSI\n   config accesses in vfio_pci_config_rw_single() then dereference and\n   call the freed perm->readfn / perm->writefn function pointers.\n\n2. Double free. A later vfio_config_free() runs free_perm_bits() and\n   kfree() on the already-freed object.\n\nFix it by NULLing vdev->msi_perm after the kfree(), matching the\nNULL-after-free discipline already used in free_perm_bits() and\nvfio_config_free().\n\n  BUG: KASAN: slab-use-after-free in vfio_pci_config_rw_single (drivers/vfio/pci/vfio_pci_config.c:1961)\n  Read of size 8 at addr ffff88800fcc88d0 by task exploit/143\n  Call Trace:\n   ...\n   kasan_report (mm/kasan/report.c:595)\n   vfio_pci_config_rw_single (drivers/vfio/pci/vfio_pci_config.c:1961)\n   vfio_pci_config_rw (drivers/vfio/pci/vfio_pci_config.c:1986)\n   vfio_pci_rw (drivers/vfio/pci/vfio_pci_core.c:1599)\n   vfs_read (fs/read_write.c:572)\n   __x64_sys_pread64 (fs/read_write.c:764)\n   do_syscall_64 (arch/x86/entry/syscall_64.c:94)\n   ...\n\nFollowed on device close by a double free of the same object:\n\n  Oops: general protection fault, probably for non-canonical address\n    0x1f63e0e8000008: 0000 [#1] SMP KASAN NOPTI\n  RIP: 0010:kfree (mm/slub.c:6711)\n  Call Trace:\n   vfio_config_free (drivers/vfio/pci/vfio_pci_config.c:1861)\n   vfio_pci_core_disable (drivers/vfio/pci/vfio_pci_core.c:685)\n   vfio_pci_core_close_device (drivers/vfio/pci/vfio_pci_core.c:777)\n   vfio_df_close (drivers/vfio/vfio_main.c:602)\n   vfio_device_fops_release (drivers/vfio/vfio_main.c:648)\n   __fput (fs/file_table.c:512)\n   __x64_sys_close (fs/open.c:1496)\n   do_syscall_64 (arch/x86/entry/syscall_64.c:94)\n   ...\n  Kernel panic - not syncing: Fatal exception"}],"metrics":[{"cvssV3_1":{"baseScore":8.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:L - The UAF is reached only via local VFIO char-device operations: open of /dev/vfio/$GROUP or /dev/vfio/devices/vfioN, then pread/pwrite of the PCI config region through vfio_pci_core_read/write into vfio_pci_config_rw_single(). There is no network or packet path into vfio_msi_cap_len().\nAC:L - After any failed vfio_config_init() plants the dangling vdev->msi_perm, the attacker retries GET_DEVICE_FD/BIND_IOMMUFD on the same persistent vdev and deterministically calls the freed perm->readfn/writefn via MSI config accesses. The attacker controls that open/read sequence; no victim race or uncontrolled layout is required.\nPR:L - vfio_pci_core_enable() and vfio_pci_config_rw() have no capable() check on the normal IOMMU path (CAP_SYS_RAWIO is only for noiommu). Access is gated by /dev/vfio node permissions, which libvirt, kubevirt, and cloud GPU/NIC passthrough routinely grant to an unprivileged qemu user or tenant.\nUI:N - The attacker performs the VFIO open, retry, and MSI config-space pread/pwrite themselves. Prior admin binding of the PCI device to vfio-pci is deployment configuration, not victim interaction during exploitation.\nS:C - struct vfio_pci_core_device persists across open/close, so a failed open can leave a dangling msi_perm that a later tenant VM reuses. QEMU services guest PCI config cycles with VFIO pread/pwrite, so a passthrough guest can invoke the freed host function pointers and cross the VFIO/IOMMU guest-to-host boundary.\nC:H - The next successful open reuses the freed perm_bits and MSI config reads call perm->readfn on that object. Reclaiming the slab slot yields an arbitrary kernel-read primitive, which CVSS kernel guidance scores High for use-after-free.\nI:H - MSI config writes call the freed perm->writefn, and a later close double-frees the same object in vfio_config_free(). That UAF/double-free of a structure with function pointers is exploitable for arbitrary kernel write and control-flow hijack.\nA:H - The report shows a KASAN slab-use-after-free in vfio_pci_config_rw_single() followed by a general-protection fault in kfree() during vfio_config_free() that panics the host, so availability impact is a kernel oops/panic."}]}],"providerMetadata":{"dateUpdated":"2026-09-16T14:38:28.611Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/eb84cd81040e58dd05ac190f561f2115e3367249"},{"url":"https://git.kernel.org/stable/c/f0eea8f9013676b42289ec35941e848b8a543e19"},{"url":"https://git.kernel.org/stable/c/d665a1688af7f8fefd7c0eb04f2a37122ce007f4"},{"url":"https://git.kernel.org/stable/c/25cdd2a492d868cff1e519a60fe282909c52d385"},{"url":"https://git.kernel.org/stable/c/812f1db7f0755a19ef16ecdc5cec51bcabc5eda5"},{"url":"https://git.kernel.org/stable/c/533d0c5feef85ee6404b9f41d5564fac6971a008"},{"url":"https://git.kernel.org/stable/c/fda8fb7e8179561693a786a7af593f6b944a21c1"},{"url":"https://git.kernel.org/stable/c/dc77acfeb979dded39b247b60fef0399536bfa77"}],"title":"vfio/pci: clear vdev->msi_perm after freeing it on init failure","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-89777","datePublished":"2026-09-16T08:48:17.754Z","dateReserved":"2026-09-11T19:38:34.765Z","dateUpdated":"2026-09-16T14:38:28.611Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-16 09:17:08","lastModifiedDate":"2026-09-16 15:18:06","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","baseScore":8.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"CHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":2,"impactScore":6}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"89777","Ordinal":"1","Title":"vfio/pci: clear vdev->msi_perm after freeing it on init failure","CVE":"CVE-2026-89777","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"89777","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nvfio/pci: clear vdev->msi_perm after freeing it on init failure\n\nvfio_msi_cap_len() lazily allocates the per-device MSI permission table:\n\n\tvdev->msi_perm = kmalloc_obj(struct perm_bits, GFP_KERNEL_ACCOUNT);\n\tif (!vdev->msi_perm)\n\t\treturn -ENOMEM;\n\n\tret = init_pci_cap_msi_perm(vdev->msi_perm, len, flags);\n\tif (ret) {\n\t\tkfree(vdev->msi_perm);\n\t\treturn ret;\t\t/* vdev->msi_perm left dangling */\n\t}\n\nWhen init_pci_cap_msi_perm() -> alloc_perm_bits() fails with -ENOMEM, the\nerror path frees vdev->msi_perm but leaves the freed pointer stored in\nit. vdev->msi_perm is not re-zeroed later because struct\nvfio_pci_core_device is per-device and persists across open/close cycles,\nand the vfio_config_init() error path returns without calling\nvfio_config_free(). So the dangling pointer outlives the failed open.\n\nThat leads to two use-after-frees on the same device:\n\n1. Reuse. The next vfio_config_init() sees the stale pointer at\n   \"if (vdev->msi_perm) return len;\" and reuses the freed object. MSI\n   config accesses in vfio_pci_config_rw_single() then dereference and\n   call the freed perm->readfn / perm->writefn function pointers.\n\n2. Double free. A later vfio_config_free() runs free_perm_bits() and\n   kfree() on the already-freed object.\n\nFix it by NULLing vdev->msi_perm after the kfree(), matching the\nNULL-after-free discipline already used in free_perm_bits() and\nvfio_config_free().\n\n  BUG: KASAN: slab-use-after-free in vfio_pci_config_rw_single (drivers/vfio/pci/vfio_pci_config.c:1961)\n  Read of size 8 at addr ffff88800fcc88d0 by task exploit/143\n  Call Trace:\n   ...\n   kasan_report (mm/kasan/report.c:595)\n   vfio_pci_config_rw_single (drivers/vfio/pci/vfio_pci_config.c:1961)\n   vfio_pci_config_rw (drivers/vfio/pci/vfio_pci_config.c:1986)\n   vfio_pci_rw (drivers/vfio/pci/vfio_pci_core.c:1599)\n   vfs_read (fs/read_write.c:572)\n   __x64_sys_pread64 (fs/read_write.c:764)\n   do_syscall_64 (arch/x86/entry/syscall_64.c:94)\n   ...\n\nFollowed on device close by a double free of the same object:\n\n  Oops: general protection fault, probably for non-canonical address\n    0x1f63e0e8000008: 0000 [#1] SMP KASAN NOPTI\n  RIP: 0010:kfree (mm/slub.c:6711)\n  Call Trace:\n   vfio_config_free (drivers/vfio/pci/vfio_pci_config.c:1861)\n   vfio_pci_core_disable (drivers/vfio/pci/vfio_pci_core.c:685)\n   vfio_pci_core_close_device (drivers/vfio/pci/vfio_pci_core.c:777)\n   vfio_df_close (drivers/vfio/vfio_main.c:602)\n   vfio_device_fops_release (drivers/vfio/vfio_main.c:648)\n   __fput (fs/file_table.c:512)\n   __x64_sys_close (fs/open.c:1496)\n   do_syscall_64 (arch/x86/entry/syscall_64.c:94)\n   ...\n  Kernel panic - not syncing: Fatal exception","Type":"Description","Title":"vfio/pci: clear vdev->msi_perm after freeing it on init failure"}]}}}