CVE-2026-98469 (GCVE-0-2026-98469)

Vulnerability from cvelistv5 – Published: 2026-10-18 15:15 – Updated: 2026-10-24 14:08
VLAI
Title
KVM: arm64: Fix AArch32 DBGBXVR<n> handling
Summary
In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Fix AArch32 DBGBXVR<n> handling The consolidation of the breakpoint and watchpoint register accessors switched DBGBXVR<n> from trap_bvr() to trap_dbg_wb_reg(). The latter selects backing storage with demux_wb_reg(), which only handles Op2 values 4 through 7. Since DBGBXVR<n> uses Op2 1, an AArch32 guest access hits KVM_BUG_ON() and marks the VM dead. DBGBXVR<n> aliases DBGBVR<n>_EL1[63:32], and its AA32(HI) descriptor already selects the upper half. Map Op2 1 to dbg_bvr[] alongside Op2 4, restoring the pre-regression behavior.
Severity
7.1 (High)
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6639 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 3ce9f3357e9e099f02feaa002769eb99ef1138cd , < 8530a05b304d312fe7dfbc5df7d3e87cc31b256a (git)
Affected: 3ce9f3357e9e099f02feaa002769eb99ef1138cd , < af6813d16ace2765011ca1c567be86ade1d1ee8e (git)
Affected: 3ce9f3357e9e099f02feaa002769eb99ef1138cd , < 6b1bca1b1ab77f60a62087337bfe6e2f0efb9e6d (git)
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Linux Linux Affected: 6.14
Unaffected: 0 , < 6.14 (semver)
Unaffected: 6.18.55 , ≤ 6.18.* (semver)
Unaffected: 7.2.9 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/arm64/kvm/sys_regs.c"
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          "versions": [
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              "versionType": "semver"
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              "version": "7.3",
              "versionType": "original_commit_for_fix"
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      "cpeApplicability": [
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          "nodes": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "vulnerable": true
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              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: arm64: Fix AArch32 DBGBXVR\u003cn\u003e handling\n\nThe consolidation of the breakpoint and watchpoint register accessors\nswitched DBGBXVR\u003cn\u003e from trap_bvr() to trap_dbg_wb_reg(). The latter\nselects backing storage with demux_wb_reg(), which only handles Op2 values\n4 through 7. Since DBGBXVR\u003cn\u003e uses Op2 1, an AArch32 guest access hits\nKVM_BUG_ON() and marks the VM dead.\n\nDBGBXVR\u003cn\u003e aliases DBGBVR\u003cn\u003e_EL1[63:32], and its AA32(HI) descriptor\nalready selects the upper half. Map Op2 1 to dbg_bvr[] alongside Op2 4,\nrestoring the pre-regression behavior."
        }
      ],
      "metrics": [
        {
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
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              "lang": "en",
              "value": "AV:L - The trigger is an AArch32 EL1 MRC/MCR to CP14 DBGBXVR\u003cn\u003e during KVM_RUN; handle_exit() dispatches CP14_MR through kvm_handle_cp14_32() and trap_dbg_wb_reg() to the patched demux_wb_reg(). No network or physical input reaches this path.\nAC:L - On a host advertising KVM_CAP_ARM_EL1_32BIT, the attacker makes DBGBXVR\u003cn\u003e the first debug-register access; kvm_arm_setup_mdcr_el2() sets TDA while debug_owner is FREE, so Op2 1 deterministically reaches demux_wb_reg()\u0027s default case. No race or uncontrollable state is involved.\nPR:N - DBGBXVR\u003cn\u003e is UNDEFINED at guest EL0 and must execute at guest EL1, but a tenant controlling its AArch32 guest kernel holds no privilege in the vulnerable host KVM authority. The trapped CP14_MR path performs no host credential or capability check.\nUI:N - The attacker directly executes the DBGBXVR\u003cn\u003e instruction, and the existing KVM_RUN loop processes the resulting CP14_MR exit automatically. No host operator or other victim must act.\nS:C - The defect executes in host KVM\u0027s demux_wb_reg(), while KVM_BUG_ON() invokes kvm_vm_bugged() and kvm_vm_dead() to disable the guest VM. Availability damage therefore crosses the host-hypervisor/guest security boundary.\nC:N - demux_wb_reg() calls KVM_BUG_ON() and returns NULL, after which trap_dbg_wb_reg() returns without calling dbg_to_reg(). No host or guest memory is exposed.\nI:N - Because demux_wb_reg() returns NULL before reg_to_dbg(), the access performs no attacker-controlled write or memory corruption. Only the deliberate vm_bugged/vm_dead error state and vCPU request are set.\nA:H - KVM_BUG_ON() leads through kvm_vm_bugged() to kvm_vm_dead(), which sets vm_dead and sends KVM_REQ_VM_DEAD to every vCPU. check_vcpu_requests() and subsequent vCPU ioctls return -EIO, making the entire VM permanently unrunnable."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-24T14:08:59.643Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/8530a05b304d312fe7dfbc5df7d3e87cc31b256a"
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          "url": "https://git.kernel.org/stable/c/af6813d16ace2765011ca1c567be86ade1d1ee8e"
        },
        {
          "url": "https://git.kernel.org/stable/c/6b1bca1b1ab77f60a62087337bfe6e2f0efb9e6d"
        }
      ],
      "title": "KVM: arm64: Fix AArch32 DBGBXVR\u003cn\u003e handling",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98469",
    "datePublished": "2026-10-18T15:15:22.065Z",
    "dateReserved": "2026-09-25T10:25:14.351Z",
    "dateUpdated": "2026-10-24T14:08:59.643Z",
    "state": "PUBLISHED"
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      "percentile": "0.06934"
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      "cve": "CVE-2026-98469",
      "id": "msrc_CVE-2026-98469",
      "initial_release_date": "2026-10-20T22:23:49.000Z",
      "product_status:under_investigation": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "KVM: arm64: Fix AArch32 DBGBXVR\u003cn\u003e handling",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-98469.json",
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        "descriptions": [
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            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: arm64: Fix AArch32 DBGBXVR\u003cn\u003e handling\n\nThe consolidation of the breakpoint and watchpoint register accessors\nswitched DBGBXVR\u003cn\u003e from trap_bvr() to trap_dbg_wb_reg(). The latter\nselects backing storage with demux_wb_reg(), which only handles Op2 values\n4 through 7. Since DBGBXVR\u003cn\u003e uses Op2 1, an AArch32 guest access hits\nKVM_BUG_ON() and marks the VM dead.\n\nDBGBXVR\u003cn\u003e aliases DBGBVR\u003cn\u003e_EL1[63:32], and its AA32(HI) descriptor\nalready selects the upper half. Map Op2 1 to dbg_bvr[] alongside Op2 4,\nrestoring the pre-regression behavior."
          }
        ],
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        "lastModified": "2026-10-24T14:16:43.323",
        "metrics": {
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                "confidentialityImpact": "NONE",
                "integrityImpact": "NONE",
                "privilegesRequired": "NONE",
                "scope": "CHANGED",
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              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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        "vulnStatus": "Received"
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      "current_release_date": "2026-11-07T11:30:07+00:00",
      "cve": "CVE-2026-98469",
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      "initial_release_date": "2026-10-18T00:00:00+00:00",
      "product_status:known_affected": "1",
      "product_status:known_not_affected": "202",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: KVM: arm64: Fix AArch32 DBGBXVR\u003cn\u003e handling",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98469.json",
      "version": "3"
    }
  }
}



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