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CVE-2026-89513 (GCVE-0-2026-89513)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:43 – Updated: 2026-09-13 06:30
VLAI
Title
RISC-V: KVM: Fix PMU event info array size overflow
Summary
In the Linux kernel, the following vulnerability has been resolved: RISC-V: KVM: Fix PMU event info array size overflow SBI PMU EVENT_GET_INFO stores guest-controlled num_events * sizeof(*einfo) in a 32-bit integer. On RV64, num_events = 0x10000001 makes 0x100000010 truncate to 16. KVM then allocates one entry but loops over the original num_events, causing out-of-bounds reads and writes. A nested guest triggered: BUG: KASAN: slab-out-of-bounds in kvm_riscv_vcpu_pmu_event_info+0xa4/0x142 Read of size 4 at addr ff600000074d46b0 by task init/1 Call Trace: [<ffffffff8006471c>] kvm_riscv_vcpu_pmu_event_info+0xa4/0x142 [<ffffffff800690c0>] kvm_sbi_ext_pmu_handler+0xca/0x268 [<ffffffff8006779e>] kvm_riscv_vcpu_sbi_ecall+0xec/0x1e6 [<ffffffff8006008c>] kvm_riscv_vcpu_exit+0x48c/0x540 [<ffffffff8005ea0a>] kvm_arch_vcpu_ioctl_run+0x37e/0xc80 Allocated by task 1: __kmalloc_noprof+0x19e/0x4b0 kvm_riscv_vcpu_pmu_event_info+0x72/0x142 kvm_sbi_ext_pmu_handler+0xca/0x268 kvm_riscv_vcpu_sbi_ecall+0xec/0x1e6 kvm_riscv_vcpu_exit+0x48c/0x540 kvm_arch_vcpu_ioctl_run+0x37e/0xc80 The buggy address is located 0 bytes to the right of allocated 16-byte region [ff600000074d46a0, ff600000074d46b0) Store the shared-memory size in size_t and reject multiplication overflow. Allocate the guest-driven array with GFP_KERNEL_ACCOUNT so it is charged to kmemcg, and use __GFP_NOWARN to suppress allocation failure warnings. Use kvcalloc() to allow vmalloc fallback and an unsigned long loop index to match num_events.
Severity
8.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: e309fd113b9f6c34672a487be08fecb7e12e7e29 , < 82088f88c96b99c27a974d09b02c2b133262fadf (git)
Affected: e309fd113b9f6c34672a487be08fecb7e12e7e29 , < 735bc20c24187ca419c9d5e63860a54b91be34bd (git)
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Linux Linux Affected: 6.18
Unaffected: 0 , < 6.18 (semver)
Unaffected: 7.2.4 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/riscv/kvm/vcpu_pmu.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "82088f88c96b99c27a974d09b02c2b133262fadf",
              "status": "affected",
              "version": "e309fd113b9f6c34672a487be08fecb7e12e7e29",
              "versionType": "git"
            },
            {
              "lessThan": "735bc20c24187ca419c9d5e63860a54b91be34bd",
              "status": "affected",
              "version": "e309fd113b9f6c34672a487be08fecb7e12e7e29",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "arch/riscv/kvm/vcpu_pmu.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.18"
            },
            {
              "lessThan": "6.18",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.4",
              "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": "7.2.4",
                  "versionStartIncluding": "6.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3-rc1",
                  "versionStartIncluding": "6.18",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nRISC-V: KVM: Fix PMU event info array size overflow\n\nSBI PMU EVENT_GET_INFO stores guest-controlled num_events * sizeof(*einfo)\nin a 32-bit integer. On RV64, num_events = 0x10000001 makes 0x100000010\ntruncate to 16. KVM then allocates one entry but loops over the original\nnum_events, causing out-of-bounds reads and writes. A nested guest\ntriggered:\n\nBUG: KASAN: slab-out-of-bounds in kvm_riscv_vcpu_pmu_event_info+0xa4/0x142\nRead of size 4 at addr ff600000074d46b0 by task init/1\nCall Trace:\n[\u003cffffffff8006471c\u003e] kvm_riscv_vcpu_pmu_event_info+0xa4/0x142\n[\u003cffffffff800690c0\u003e] kvm_sbi_ext_pmu_handler+0xca/0x268\n[\u003cffffffff8006779e\u003e] kvm_riscv_vcpu_sbi_ecall+0xec/0x1e6\n[\u003cffffffff8006008c\u003e] kvm_riscv_vcpu_exit+0x48c/0x540\n[\u003cffffffff8005ea0a\u003e] kvm_arch_vcpu_ioctl_run+0x37e/0xc80\nAllocated by task 1:\n __kmalloc_noprof+0x19e/0x4b0\n kvm_riscv_vcpu_pmu_event_info+0x72/0x142\n kvm_sbi_ext_pmu_handler+0xca/0x268\n kvm_riscv_vcpu_sbi_ecall+0xec/0x1e6\n kvm_riscv_vcpu_exit+0x48c/0x540\n kvm_arch_vcpu_ioctl_run+0x37e/0xc80\nThe buggy address is located 0 bytes to the right of\n allocated 16-byte region [ff600000074d46a0, ff600000074d46b0)\n\nStore the shared-memory size in size_t and reject multiplication overflow.\nAllocate the guest-driven array with GFP_KERNEL_ACCOUNT so it is charged\nto kmemcg, and use __GFP_NOWARN to suppress allocation failure warnings.\nUse kvcalloc() to allow vmalloc fallback and an unsigned long loop index\nto match num_events."
        }
      ],
      "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 overflow is reached when a RISC-V KVM guest issues an SBI ECALL (EXC_SUPERVISOR_SYSCALL) for SBI_EXT_PMU_EVENT_GET_INFO, handled on the host KVM_RUN path via kvm_riscv_vcpu_exit, kvm_riscv_vcpu_sbi_ecall, kvm_sbi_ext_pmu_handler, and kvm_riscv_vcpu_pmu_event_info; this is a local guest hypercall path with no network or physical exposure.\nAC:L - A guest that sets flags=0, a 16-byte-aligned shared-memory GPA, and num_events=0x10000001 on RV64 makes num_events*sizeof(*einfo) truncate from 0x100000010 to 16, so kzalloc gets one entry while the loop uses the original count; the attacker controls every parameter and needs no race or uncontrollable host layout.\nPR:L - Issuing the SBI ECALL requires VS-mode in a KVM guest (tenant kernel or custom image) or a host kvm-group user running QEMU, not host init-namespace root; kvm_sbi_ext_pmu_handler has no capability check, and SBI PMU is enabled by default once kvm_riscv_vcpu_pmu_init succeeds.\nUI:N - The attacker guest issues SBI_EXT_PMU_EVENT_GET_INFO itself during KVM_RUN; no separate victim action such as attaching a device, mounting a filesystem, or confirming a prompt is required.\nS:C - The slab out-of-bounds access runs in the host kernel while handling a guest SBI call, crossing the KVM guest-to-hypervisor boundary so host heap corruption can compromise the hypervisor and co-located VMs, which CNA guidance rates Changed for KVM guest-to-host escape.\nC:H - After the truncated 16-byte allocation, the loop reads event_idx and event_data from adjacent host slab for 0x10000001 entries; that unbounded host-heap out-of-bounds read, together with the following heap corruption, can be leveraged for kernel memory disclosure.\nI:H - The same loop writes einfo[i].output (0 or 1) past the 16-byte object at a 16-byte stride for about 2^28 iterations, an unbounded host-slab out-of-bounds write that smashes neighboring objects and heap metadata and is scored High per CNA out-of-bounds-write guidance.\nA:H - KASAN reported a host slab-out-of-bounds in kvm_riscv_vcpu_pmu_event_info, and walking billions of bytes past a 16-byte allocation reliably oopses or panics the host kernel, denying service to the hypervisor and every co-located VM."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-13T06:30:17.247Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/82088f88c96b99c27a974d09b02c2b133262fadf"
        },
        {
          "url": "https://git.kernel.org/stable/c/735bc20c24187ca419c9d5e63860a54b91be34bd"
        }
      ],
      "title": "RISC-V: KVM: Fix PMU event info array size overflow",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89513",
    "datePublished": "2026-09-11T19:43:57.960Z",
    "dateReserved": "2026-09-11T19:38:34.717Z",
    "dateUpdated": "2026-09-13T06:30:17.247Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-89513",
      "date": "2026-09-15",
      "epss": "0.0012",
      "percentile": "0.02099"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-89513\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-09-11T20:19:33.787\",\"lastModified\":\"2026-09-13T07:17:14.203\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nRISC-V: KVM: Fix PMU event info array size overflow\\n\\nSBI PMU EVENT_GET_INFO stores guest-controlled num_events * sizeof(*einfo)\\nin a 32-bit integer. On RV64, num_events = 0x10000001 makes 0x100000010\\ntruncate to 16. KVM then allocates one entry but loops over the original\\nnum_events, causing out-of-bounds reads and writes. A nested guest\\ntriggered:\\n\\nBUG: KASAN: slab-out-of-bounds in kvm_riscv_vcpu_pmu_event_info+0xa4/0x142\\nRead of size 4 at addr ff600000074d46b0 by task init/1\\nCall Trace:\\n[\u003cffffffff8006471c\u003e] kvm_riscv_vcpu_pmu_event_info+0xa4/0x142\\n[\u003cffffffff800690c0\u003e] kvm_sbi_ext_pmu_handler+0xca/0x268\\n[\u003cffffffff8006779e\u003e] kvm_riscv_vcpu_sbi_ecall+0xec/0x1e6\\n[\u003cffffffff8006008c\u003e] kvm_riscv_vcpu_exit+0x48c/0x540\\n[\u003cffffffff8005ea0a\u003e] kvm_arch_vcpu_ioctl_run+0x37e/0xc80\\nAllocated by task 1:\\n __kmalloc_noprof+0x19e/0x4b0\\n kvm_riscv_vcpu_pmu_event_info+0x72/0x142\\n kvm_sbi_ext_pmu_handler+0xca/0x268\\n kvm_riscv_vcpu_sbi_ecall+0xec/0x1e6\\n kvm_riscv_vcpu_exit+0x48c/0x540\\n kvm_arch_vcpu_ioctl_run+0x37e/0xc80\\nThe buggy address is located 0 bytes to the right of\\n allocated 16-byte region [ff600000074d46a0, ff600000074d46b0)\\n\\nStore the shared-memory size in size_t and reject multiplication overflow.\\nAllocate the guest-driven array with GFP_KERNEL_ACCOUNT so it is charged\\nto kmemcg, and use __GFP_NOWARN to suppress allocation failure warnings.\\nUse kvcalloc() to allow vmalloc fallback and an unsigned long loop index\\nto match num_events.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"arch/riscv/kvm/vcpu_pmu.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"e309fd113b9f6c34672a487be08fecb7e12e7e29\",\"lessThan\":\"82088f88c96b99c27a974d09b02c2b133262fadf\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"e309fd113b9f6c34672a487be08fecb7e12e7e29\",\"lessThan\":\"735bc20c24187ca419c9d5e63860a54b91be34bd\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"arch/riscv/kvm/vcpu_pmu.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"6.18\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"6.18\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2.4\",\"lessThanOrEqual\":\"7.2.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.3-rc1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"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\":2.0,\"impactScore\":6.0}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/735bc20c24187ca419c9d5e63860a54b91be34bd\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/82088f88c96b99c27a974d09b02c2b133262fadf\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2026-09-13T06:49:47+00:00",
      "cve": "CVE-2026-89513",
      "id": "CVE-2026-89513",
      "initial_release_date": "2026-09-11T19:43:57.960000+00:00",
      "product_status:known_affected": "2",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: Linux kernel KVM (RISC-V): Memory corruption due to PMU event info array overflow",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89513.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "important",
      "current_release_date": "2026-09-12T16:27:09Z",
      "cve": "CVE-2026-89513",
      "id": "CVE-2026-89513",
      "initial_release_date": "2026-09-12T16:27:09Z",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-89513",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-89513.json",
      "version": "2"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.