{
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"cveMetadata": {
"cveId": "CVE-2026-23198",
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"state": "PUBLISHED",
"assignerShortName": "Linux",
"dateReserved": "2026-01-13T15:37:45.985Z",
"datePublished": "2026-02-14T16:27:23.621Z",
"dateUpdated": "2026-08-05T12:20:38.053Z"
},
"containers": {
"cna": {
"providerMetadata": {
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux",
"dateUpdated": "2026-08-05T12:20:38.053Z"
},
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: Don't clobber irqfd routing type when deassigning irqfd\n\nWhen deassigning a KVM_IRQFD, don't clobber the irqfd's copy of the IRQ's\nrouting entry as doing so breaks kvm_arch_irq_bypass_del_producer() on x86\nand arm64, which explicitly look for KVM_IRQ_ROUTING_MSI. Instead, to\nhandle a concurrent routing update, verify that the irqfd is still active\nbefore consuming the routing information. As evidenced by the x86 and\narm64 bugs, and another bug in kvm_arch_update_irqfd_routing() (see below),\nclobbering the entry type without notifying arch code is surprising and\nerror prone.\n\nAs a bonus, checking that the irqfd is active provides a convenient\nlocation for documenting _why_ KVM must not consume the routing entry for\nan irqfd that is in the process of being deassigned: once the irqfd is\ndeleted from the list (which happens *before* the eventfd is detached), it\nwill no longer receive updates via kvm_irq_routing_update(), and so KVM\ncould deliver an event using stale routing information (relative to\nKVM_SET_GSI_ROUTING returning to userspace).\n\nAs an even better bonus, explicitly checking for the irqfd being active\nfixes a similar bug to the one the clobbering is trying to prevent: if an\nirqfd is deactivated, and then its routing is changed,\nkvm_irq_routing_update() won't invoke kvm_arch_update_irqfd_routing()\n(because the irqfd isn't in the list). And so if the irqfd is in bypass\nmode, IRQs will continue to be posted using the old routing information.\n\nAs for kvm_arch_irq_bypass_del_producer(), clobbering the routing type\nresults in KVM incorrectly keeping the IRQ in bypass mode, which is\nespecially problematic on AMD as KVM tracks IRQs that are being posted to\na vCPU in a list whose lifetime is tied to the irqfd.\n\nWithout the help of KASAN to detect use-after-free, the most common\nsympton on AMD is a NULL pointer deref in amd_iommu_update_ga() due to\nthe memory for irqfd structure being re-allocated and zeroed, resulting\nin irqfd->irq_bypass_data being NULL when read by\navic_update_iommu_vcpu_affinity():\n\n BUG: kernel NULL pointer dereference, address: 0000000000000018\n #PF: supervisor read access in kernel mode\n #PF: error_code(0x0000) - not-present page\n PGD 40cf2b9067 P4D 40cf2b9067 PUD 408362a067 PMD 0\n Oops: Oops: 0000 [#1] SMP\n CPU: 6 UID: 0 PID: 40383 Comm: vfio_irq_test\n Tainted: G U W O 6.19.0-smp--5dddc257e6b2-irqfd #31 NONE\n Tainted: [U]=USER, [W]=WARN, [O]=OOT_MODULE\n Hardware name: Google, Inc. Arcadia_IT_80/Arcadia_IT_80, BIOS 34.78.2-0 09/05/2025\n RIP: 0010:amd_iommu_update_ga+0x19/0xe0\n Call Trace:\n \n avic_update_iommu_vcpu_affinity+0x3d/0x90 [kvm_amd]\n __avic_vcpu_load+0xf4/0x130 [kvm_amd]\n kvm_arch_vcpu_load+0x89/0x210 [kvm]\n vcpu_load+0x30/0x40 [kvm]\n kvm_arch_vcpu_ioctl_run+0x45/0x620 [kvm]\n kvm_vcpu_ioctl+0x571/0x6a0 [kvm]\n __se_sys_ioctl+0x6d/0xb0\n do_syscall_64+0x6f/0x9d0\n entry_SYSCALL_64_after_hwframe+0x4b/0x53\n RIP: 0033:0x46893b\n \n ---[ end trace 0000000000000000 ]---\n\nIf AVIC is inhibited when the irfd is deassigned, the bug will manifest as\nlist corruption, e.g. on the next irqfd assignment.\n\n list_add corruption. next->prev should be prev (ffff8d474d5cd588),\n but was 0000000000000000. (next=ffff8d8658f86530).\n ------------[ cut here ]------------\n kernel BUG at lib/list_debug.c:31!\n Oops: invalid opcode: 0000 [#1] SMP\n CPU: 128 UID: 0 PID: 80818 Comm: vfio_irq_test\n Tainted: G U W O 6.19.0-smp--f19dc4d680ba-irqfd #28 NONE\n Tainted: [U]=USER, [W]=WARN, [O]=OOT_MODULE\n Hardware name: Google, Inc. Arcadia_IT_80/Arcadia_IT_80, BIOS 34.78.2-0 09/05/2025\n RIP: 0010:__list_add_valid_or_report+0x97/0xc0\n Call Trace:\n \n avic_pi_update_irte+0x28e/0x2b0 [kvm_amd]\n kvm_pi_update_irte+0xbf/0x190 [kvm]\n kvm_arch_irq_bypass_add_producer+0x72/0x90 [kvm]\n irq_bypass_register_consumer+0xcd/0x170 [irqbypa\n---truncated---"
}
],
"metrics": [
{
"cvssV3_1": {
"version": "3.1",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"baseScore": 7.8,
"baseSeverity": "HIGH"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - The vulnerability is triggered via the KVM_IRQFD ioctl on a KVM VM file descriptor, which requires local access to the system and /dev/kvm.\nAC:L - The bug is deterministic - deassigning an irqfd always clobbers irq_entry.type, causing the bypass cleanup to be skipped. The attacker controls both the assign and deassign operations, so no uncontrollable conditions exist.\nPR:L - Access to /dev/kvm is typically available to unprivileged users who are members of the kvm group or in configurations where KVM is broadly accessible; real root privileges are not required.\nUI:N - No user interaction is needed; the attacker can trigger the vulnerability entirely through their own ioctl calls on a KVM VM they created.\nS:U - The vulnerability affects the host kernel from a host-side user operating KVM. It does not cross a guest-to-host security boundary; the attacker is already on the host.\nC:H - The use-after-free on the irqfd structure allows an attacker to read contents of freed and potentially reallocated memory, providing an arbitrary read primitive through heap manipulation.\nI:H - The use-after-free and list corruption (ir_list) enable heap spraying into the freed irqfd structure, giving arbitrary write primitives and potential code execution via control flow hijacking.\nA:H - The bug directly causes NULL pointer dereferences and list corruption BUGs, resulting in kernel oops/panic as demonstrated in the commit message's crash traces."
}
]
}
],
"affected": [
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "unaffected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"virt/kvm/eventfd.c"
],
"versions": [
{
"version": "f70c20aaf141adb715a2d750c55154073b02a9c3",
"lessThan": "959a063e7f12524bc1871ad1f519787967bbcd45",
"status": "affected",
"versionType": "git"
},
{
"version": "f70c20aaf141adb715a2d750c55154073b02a9c3",
"lessThan": "2284bc168b148a17b5ca3b37b3d95c411f18a08d",
"status": "affected",
"versionType": "git"
},
{
"version": "f70c20aaf141adb715a2d750c55154073b02a9c3",
"lessThan": "6d14ba1e144e796b5fc81044f08cfba9024ca195",
"status": "affected",
"versionType": "git"
},
{
"version": "f70c20aaf141adb715a2d750c55154073b02a9c3",
"lessThan": "b61f9b2fcf181451d0a319889478cc53c001123e",
"status": "affected",
"versionType": "git"
},
{
"version": "f70c20aaf141adb715a2d750c55154073b02a9c3",
"lessThan": "ff48c9312d042bfbe826ca675e98acc6c623211c",
"status": "affected",
"versionType": "git"
},
{
"version": "f70c20aaf141adb715a2d750c55154073b02a9c3",
"lessThan": "4385b2f2843549bfb932e0dcf76bf4b065543a3c",
"status": "affected",
"versionType": "git"
},
{
"version": "f70c20aaf141adb715a2d750c55154073b02a9c3",
"lessThan": "b4d37cdb77a0015f51fee083598fa227cc07aaf1",
"status": "affected",
"versionType": "git"
}
]
},
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "affected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"virt/kvm/eventfd.c"
],
"versions": [
{
"version": "4.4",
"status": "affected"
},
{
"version": "0",
"lessThan": "4.4",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "5.10.250",
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "5.15.200",
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "6.1.163",
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "6.6.124",
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "6.12.70",
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "6.18.10",
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "6.19",
"lessThanOrEqual": "*",
"status": "unaffected",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"operator": "OR",
"negate": false,
"cpeMatch": [
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "4.4",
"versionEndExcluding": "5.10.250"
},
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "4.4",
"versionEndExcluding": "5.15.200"
},
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "4.4",
"versionEndExcluding": "6.1.163"
},
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "4.4",
"versionEndExcluding": "6.6.124"
},
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "4.4",
"versionEndExcluding": "6.12.70"
},
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "4.4",
"versionEndExcluding": "6.18.10"
},
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "4.4",
"versionEndExcluding": "6.19"
}
]
}
]
}
],
"references": [
{
"url": "https://git.kernel.org/stable/c/959a063e7f12524bc1871ad1f519787967bbcd45"
},
{
"url": "https://git.kernel.org/stable/c/2284bc168b148a17b5ca3b37b3d95c411f18a08d"
},
{
"url": "https://git.kernel.org/stable/c/6d14ba1e144e796b5fc81044f08cfba9024ca195"
},
{
"url": "https://git.kernel.org/stable/c/b61f9b2fcf181451d0a319889478cc53c001123e"
},
{
"url": "https://git.kernel.org/stable/c/ff48c9312d042bfbe826ca675e98acc6c623211c"
},
{
"url": "https://git.kernel.org/stable/c/4385b2f2843549bfb932e0dcf76bf4b065543a3c"
},
{
"url": "https://git.kernel.org/stable/c/b4d37cdb77a0015f51fee083598fa227cc07aaf1"
}
],
"title": "KVM: Don't clobber irqfd routing type when deassigning irqfd",
"x_generator": {
"engine": "bippy-1.2.0"
}
},
"adp": [
{
"metrics": [
{
"other": {
"type": "ssvc",
"content": {
"timestamp": "2026-06-16T20:33:50.365342Z",
"id": "CVE-2026-23198",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "total"
}
],
"role": "CISA Coordinator",
"version": "2.0.3"
}
}
}
],
"title": "CISA ADP Vulnrichment",
"providerMetadata": {
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP",
"dateUpdated": "2026-06-16T20:34:00.278Z"
}
}
]
}
}