Linux Kernel up to 7.2.5 vfio_pci vfio_pci_config.c vfio_pci_config_rw_single use after free

CVSS Meta Temp Score
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CTI Interest Score
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8.4$0-$5k0.45

Summaryinfo

A vulnerability was found in Linux Kernel up to 7.2.5. It has been rated as very critical. Affected by this vulnerability is the function vfio_pci_config_rw_single of the file drivers/vfio/pci/vfio_pci_config.c of the component vfio_pci. This manipulation causes use after free. The identification of this vulnerability is CVE-2026-89777. The attack can only be executed locally. There is no exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability classified as very critical was found in Linux Kernel up to 7.2.5. Affected by this vulnerability is the function vfio_pci_config_rw_single of the file drivers/vfio/pci/vfio_pci_config.c of the component vfio_pci. The manipulation with an unknown input leads to a use after free vulnerability. The CWE definition for the vulnerability is CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: vfio/pci: clear vdev->msi_perm after freeing it on init failure vfio_msi_cap_len() lazily allocates the per-device MSI permission table: vdev->msi_perm = kmalloc_obj(struct perm_bits, GFP_KERNEL_ACCOUNT); if (!vdev->msi_perm) return -ENOMEM; ret = init_pci_cap_msi_perm(vdev->msi_perm, len, flags); if (ret) { kfree(vdev->msi_perm); return ret; /* vdev->msi_perm left dangling */ } When init_pci_cap_msi_perm() -> alloc_perm_bits() fails with -ENOMEM, the error path frees vdev->msi_perm but leaves the freed pointer stored in it. vdev->msi_perm is not re-zeroed later because struct vfio_pci_core_device is per-device and persists across open/close cycles, and the vfio_config_init() error path returns without calling vfio_config_free(). So the dangling pointer outlives the failed open. That leads to two use-after-frees on the same device: 1. Reuse. The next vfio_config_init() sees the stale pointer at "if (vdev->msi_perm) return len;" and reuses the freed object. MSI config accesses in vfio_pci_config_rw_single() then dereference and call the freed perm->readfn / perm->writefn function pointers. 2. Double free. A later vfio_config_free() runs free_perm_bits() and kfree() on the already-freed object. Fix it by NULLing vdev->msi_perm after the kfree(), matching the NULL-after-free discipline already used in free_perm_bits() and vfio_config_free(). BUG: KASAN: slab-use-after-free in vfio_pci_config_rw_single (drivers/vfio/pci/vfio_pci_config.c:1961) Read of size 8 at addr ffff88800fcc88d0 by task exploit/143 Call Trace: ... kasan_report (mm/kasan/report.c:595) vfio_pci_config_rw_single (drivers/vfio/pci/vfio_pci_config.c:1961) vfio_pci_config_rw (drivers/vfio/pci/vfio_pci_config.c:1986) vfio_pci_rw (drivers/vfio/pci/vfio_pci_core.c:1599) vfs_read (fs/read_write.c:572) __x64_sys_pread64 (fs/read_write.c:764) do_syscall_64 (arch/x86/entry/syscall_64.c:94) ... Followed on device close by a double free of the same object: Oops: general protection fault, probably for non-canonical address 0x1f63e0e8000008: 0000 [#1] SMP KASAN NOPTI RIP: 0010:kfree (mm/slub.c:6711) Call Trace: vfio_config_free (drivers/vfio/pci/vfio_pci_config.c:1861) vfio_pci_core_disable (drivers/vfio/pci/vfio_pci_core.c:685) vfio_pci_core_close_device (drivers/vfio/pci/vfio_pci_core.c:777) vfio_df_close (drivers/vfio/vfio_main.c:602) vfio_device_fops_release (drivers/vfio/vfio_main.c:648) __fput (fs/file_table.c:512) __x64_sys_close (fs/open.c:1496) do_syscall_64 (arch/x86/entry/syscall_64.c:94) ... Kernel panic - not syncing: Fatal exception

It is possible to read the advisory at git.kernel.org. This vulnerability is known as CVE-2026-89777 since 09/11/2026. The exploitation appears to be easy. Attacking locally is a requirement. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 09/16/2026).

Upgrading to version 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.110, 6.18.52, 7.2.6 or 7.3-rc1 eliminates this vulnerability. Applying the patch eb84cd81040e58dd05ac190f561f2115e3367249/f0eea8f9013676b42289ec35941e848b8a543e19/d665a1688af7f8fefd7c0eb04f2a37122ce007f4/25cdd2a492d868cff1e519a60fe282909c52d385/812f1db7f0755a19ef16ecdc5cec51bcabc5eda5/533d0c5feef85ee6404b9f41d5564fac6971a008/fda8fb7e8179561693a786a7af593f6b944a21c1/dc77acfeb979dded39b247b60fef0399536bfa77 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.8
VulDB Meta Temp Score: 8.4

VulDB Base Score: 8.8
VulDB Temp Score: 8.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
💳💳💳💳💳💳
💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: No

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.10.270/5.15.221/6.1.188/6.6.157/6.12.110/6.18.52/7.2.6/7.3-rc1
Patch: eb84cd81040e58dd05ac190f561f2115e3367249/f0eea8f9013676b42289ec35941e848b8a543e19/d665a1688af7f8fefd7c0eb04f2a37122ce007f4/25cdd2a492d868cff1e519a60fe282909c52d385/812f1db7f0755a19ef16ecdc5cec51bcabc5eda5/533d0c5feef85ee6404b9f41d5564fac6971a008/fda8fb7e8179561693a786a7af593f6b944a21c1/dc77acfeb979dded39b247b60fef0399536bfa77

Timelineinfo

09/11/2026 CVE reserved
09/16/2026 +5 days Advisory disclosed
09/16/2026 +0 days VulDB entry created
09/16/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-89777 (🔒)
GCVE (CVE): GCVE-0-2026-89777
GCVE (VulDB): GCVE-100-405559

Entryinfo

Created: 09/16/2026 11:01
Changes: 09/16/2026 11:01 (60)
Complete: 🔍
Cache ID: 216::103

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