{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-23425", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-01-13T15:37:46.015Z", "datePublished": "2026-04-03T13:24:33.384Z", "dateUpdated": "2026-08-05T12:21:39.120Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:21:39.120Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: arm64: Fix ID register initialization for non-protected pKVM guests\n\nIn protected mode, the hypervisor maintains a separate instance of\nthe `kvm` structure for each VM. For non-protected VMs, this structure is\ninitialized from the host's `kvm` state.\n\nCurrently, `pkvm_init_features_from_host()` copies the\n`KVM_ARCH_FLAG_ID_REGS_INITIALIZED` flag from the host without the\nunderlying `id_regs` data being initialized. This results in the\nhypervisor seeing the flag as set while the ID registers remain zeroed.\n\nConsequently, `kvm_has_feat()` checks at EL2 fail (return 0) for\nnon-protected VMs. This breaks logic that relies on feature detection,\nsuch as `ctxt_has_tcrx()` for TCR2_EL1 support. As a result, certain\nsystem registers (e.g., TCR2_EL1, PIR_EL1, POR_EL1) are not\nsaved/restored during the world switch, which could lead to state\ncorruption.\n\nFix this by explicitly copying the ID registers from the host `kvm` to\nthe hypervisor `kvm` for non-protected VMs during initialization, since\nwe trust the host with its non-protected guests' features. Also ensure\n`KVM_ARCH_FLAG_ID_REGS_INITIALIZED` is cleared initially in\n`pkvm_init_features_from_host` so that `vm_copy_id_regs` can properly\ninitialize them and set the flag once done." } ], "metrics": [ { "cvssV3_1": { "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" }, "scenarios": [ { "lang": "en", "value": "AV:L - The vulnerable pKVM path is reached by a local attacker able to create and run an arm64 KVM VM through /dev/kvm ioctls, not by network or adjacent traffic.\nAC:L - The trigger is deterministic on affected pKVM systems: create/run a non-protected VM and execute guest EL1 system-register operations; there is no attacker-uncontrolled race.\nPR:L - The attacker needs local permission to use /dev/kvm and run a VM, but the kernel path does not require real root or CAP_SYS_ADMIN once that device access exists.\nUI:N - No victim interaction is required after the attacker runs the malicious VM workload.\nS:C - The bug crosses the KVM guest/host security boundary because guest-controlled CPU system-register state can be left active when returning to the host.\nC:H - Skipped save/restore of TCR2/PIR/POR-class registers can expose stale host or other-context register state and can plausibly undermine host memory permission behavior, so the highest defensible confidentiality impact is high.\nI:H - A malicious guest can corrupt host EL1 translation and permission-overlay state across the world switch, plausibly enabling unauthorized host memory modification or control-flow compromise.\nA:H - Corrupting host MMU and permission-control registers can reliably crash or destabilize the host kernel, and the attacker can repeat the trigger via KVM_RUN." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "arch/arm64/kvm/hyp/nvhe/pkvm.c" ], "versions": [ { "version": "41d6028e28bd474298ff10409c292ec46cf43a90", "lessThan": "bce3847f7c51b86332bf2e554c9e80ca3820f16c", "status": "affected", "versionType": "git" }, { "version": "41d6028e28bd474298ff10409c292ec46cf43a90", "lessThan": "858620655c1fbff05997e162fc7d83a3293d5142", "status": "affected", "versionType": "git" }, { "version": "41d6028e28bd474298ff10409c292ec46cf43a90", "lessThan": "7e7c2cf0024d89443a7af52e09e47b1fe634ab17", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "arch/arm64/kvm/hyp/nvhe/pkvm.c" ], "versions": [ { "version": "6.14", "status": "affected" }, { "version": "0", "lessThan": "6.14", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.17", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.19.7", "lessThanOrEqual": "6.19.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0", "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": "6.14", "versionEndExcluding": "6.18.17" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.14", "versionEndExcluding": "6.19.7" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.14", "versionEndExcluding": "7.0" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/bce3847f7c51b86332bf2e554c9e80ca3820f16c" }, { "url": "https://git.kernel.org/stable/c/858620655c1fbff05997e162fc7d83a3293d5142" }, { "url": "https://git.kernel.org/stable/c/7e7c2cf0024d89443a7af52e09e47b1fe634ab17" } ], "title": "KVM: arm64: Fix ID register initialization for non-protected pKVM guests", "x_generator": { "engine": "bippy-1.2.0" } } } }