{"id":"CVE-2026-98469","state":"PUBLISHED","title":"KVM: arm64: Fix AArch32 DBGBXVR<n> handling","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: arm64: Fix AArch32 DBGBXVR<n> handling\n\nThe consolidation of the breakpoint and watchpoint register accessors\nswitched DBGBXVR<n> 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<n> uses Op2 1, an AArch32 guest access hits\nKVM_BUG_ON() and marks the VM dead.\n\nDBGBXVR<n> aliases DBGBVR<n>_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.","publishedAt":"2026-10-18T15:15:22.065Z","updatedAt":"2026-10-24T14:08:59.643Z","severity":{"score":7.1,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"3ce9f3357e9e099f02feaa002769eb99ef1138cd","status":"affected","lessThan":"8530a05b304d312fe7dfbc5df7d3e87cc31b256a","versionType":"git"},{"version":"3ce9f3357e9e099f02feaa002769eb99ef1138cd","status":"affected","lessThan":"af6813d16ace2765011ca1c567be86ade1d1ee8e","versionType":"git"},{"version":"3ce9f3357e9e099f02feaa002769eb99ef1138cd","status":"affected","lessThan":"6b1bca1b1ab77f60a62087337bfe6e2f0efb9e6d","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/arm64/kvm/sys_regs.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.14","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.14","versionType":"semver"},{"version":"6.18.55","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.9","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/arm64/kvm/sys_regs.c"]}],"references":["https://git.kernel.org/stable/c/8530a05b304d312fe7dfbc5df7d3e87cc31b256a","https://git.kernel.org/stable/c/af6813d16ace2765011ca1c567be86ade1d1ee8e","https://git.kernel.org/stable/c/6b1bca1b1ab77f60a62087337bfe6e2f0efb9e6d"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:43.249Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/98xxx/CVE-2026-98469.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-98469","state":"PUBLISHED","datePublished":"2026-10-18T15:15:22.065Z","dateUpdated":"2026-10-24T14:08:59.643Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-25T10:25:14.351Z"},"containers":{"cna":{"title":"KVM: arm64: Fix AArch32 DBGBXVR<n> handling","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: arm64: Fix AArch32 DBGBXVR<n> handling\n\nThe consolidation of the breakpoint and watchpoint register accessors\nswitched DBGBXVR<n> 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<n> uses Op2 1, an AArch32 guest access hits\nKVM_BUG_ON() and marks the VM dead.\n\nDBGBXVR<n> aliases DBGBVR<n>_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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"3ce9f3357e9e099f02feaa002769eb99ef1138cd","status":"affected","lessThan":"8530a05b304d312fe7dfbc5df7d3e87cc31b256a","versionType":"git"},{"version":"3ce9f3357e9e099f02feaa002769eb99ef1138cd","status":"affected","lessThan":"af6813d16ace2765011ca1c567be86ade1d1ee8e","versionType":"git"},{"version":"3ce9f3357e9e099f02feaa002769eb99ef1138cd","status":"affected","lessThan":"6b1bca1b1ab77f60a62087337bfe6e2f0efb9e6d","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/arm64/kvm/sys_regs.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.14","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.14","versionType":"semver"},{"version":"6.18.55","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.9","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/arm64/kvm/sys_regs.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/8530a05b304d312fe7dfbc5df7d3e87cc31b256a"},{"url":"https://git.kernel.org/stable/c/af6813d16ace2765011ca1c567be86ade1d1ee8e"},{"url":"https://git.kernel.org/stable/c/6b1bca1b1ab77f60a62087337bfe6e2f0efb9e6d"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H","baseScore":7.1,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The trigger is an AArch32 EL1 MRC/MCR to CP14 DBGBXVR<n> 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<n> 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()'s default case. No race or uncontrollable state is involved.\nPR:N - DBGBXVR<n> 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<n> 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's 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":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-24T14:08:59.643Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.14","versionEndExcluding":"6.18.55"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.14","versionEndExcluding":"7.2.9"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.14","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}