{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-98283", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-25T10:25:14.335Z", "datePublished": "2026-10-06T08:45:44.593Z", "dateUpdated": "2026-10-19T09:16:54.747Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T09:16:54.747Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: PPC: Book3S HV: fix use-after-free in kvmhv_emulate_tlbie_all_lpid()\n\nkvmhv_emulate_tlbie_all_lpid() iterates the nested-guest IDR and drops\nmmu_lock before calling kvmhv_emulate_tlbie_lpid(), but does not hold a\nreference on the kvm_nested_guest pointer obtained from the IDR. A\nconcurrent vCPU issuing a single-LPID tlbie (is=2, ric=2) can race\nthrough kvmhv_flush_nested() -> kvmhv_remove_nested() -> idr_remove /\n--refcnt -> kvmhv_release_nested() -> kfree(gp) in that window, leaving\nthe iterating vCPU with a dangling pointer. The subsequent\nmutex_lock(&gp->tlb_lock) and accesses to gp->shadow_pgtable,\ngp->shadow_lpid and gp->l1_host all touch freed memory. The free path\nis fully L1-controlled.\n\nFix this by incrementing gp->refcnt inside the loop before dropping\nmmu_lock, mirroring what kvmhv_get_nested() does, and releasing the\nreference with kvmhv_put_nested() after the per-guest work completes.\nThis is the same get/put discipline already used at every other\ncall site that drops mmu_lock while holding a nested-guest pointer." } ], "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 trigger is the H_TLB_INVALIDATE hcall made by code running inside an L1 guest on the POWER KVM-HV host, via kvmppc_pseries_do_hcall -> kvmhv_do_nested_tlbie -> kvmhv_emulate_priv_tlbie -> kvmhv_emulate_tlbie_all_lpid. No network protocol carries the input; the attacker needs code execution in a local guest.\nAC:L - The L1 controls both sides of the race: one vCPU issues tlbie is=3 (all-LPID walk), another issues is=2 ric=2 after zeroing its own partition-table entry so kvmhv_flush_nested() calls kvmhv_remove_nested() and kfree(gp). Contention on gp->tlb_lock widens the window and the attempt can be repeated. The only outside requirement is the VMM enabling KVM_CAP_PPC_NESTED_HV.\nPR:L - The attacker needs kernel/hypervisor-mode code in a nested-enabled L1 guest, which an ordinary tenant owns, but holds no privilege on the L0 host. The nesting_enabled() check is the only gate before kvmhv_do_nested_tlbie().\nUI:N - The L1 guest issues every hcall and controls every partition-table entry involved. No host operator or other user has to do anything.\nS:C - A guest-controlled vulnerability corrupts memory in the L0 host kernel (the kfree'd kvm_nested_guest object), which crosses the guest-to-host boundary.\nC:H - After the free, kvmhv_emulate_tlbie_lpid() reads gp->shadow_pgtable, gp->shadow_lpid and gp->l1_host from the dangling object. A reclaimed object lets the guest steer host page-table walks and host data reads.\nI:H - The freed gp is used for mutex_lock(&gp->tlb_lock), kvmppc_free_pgtable_radix() on gp->shadow_pgtable, and kvmhv_flush_nested()/kvmhv_put_nested() refcount writes. With a reclaimed object, these become host-kernel write and free primitives the guest controls.\nA:H - Using the freed kvm_nested_guest in the host can oops or panic the L0 host kernel, taking down every guest on the machine. The L1 can trigger it again at will." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "arch/powerpc/kvm/book3s_hv_nested.c" ], "versions": [ { "version": "e3b6b4661527e821ffbe3db83952fdb1e6e47c49", "lessThan": "4d8f7b1f586375df8bce23a0909566ad5e852259", "status": "affected", "versionType": "git" }, { "version": "e3b6b4661527e821ffbe3db83952fdb1e6e47c49", "lessThan": "e37fba1ba69385cff2d0e60b371ee19e7d1852d1", "status": "affected", "versionType": "git" }, { "version": "e3b6b4661527e821ffbe3db83952fdb1e6e47c49", "lessThan": "24b634852413229bb8340d908b115c3365f3a247", "status": "affected", "versionType": "git" }, { "version": "e3b6b4661527e821ffbe3db83952fdb1e6e47c49", "lessThan": "fbf69b7d0555ee83c871f58750770f74b7179ad1", "status": "affected", "versionType": "git" }, { "version": "e3b6b4661527e821ffbe3db83952fdb1e6e47c49", "lessThan": "ec2d7a52b3996ae81131617b4afc0af31583c1b4", "status": "affected", "versionType": "git" }, { "version": "e3b6b4661527e821ffbe3db83952fdb1e6e47c49", "lessThan": "51938dfa8a51a4f85328413fca9b6e21f9d2d088", "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/powerpc/kvm/book3s_hv_nested.c" ], "versions": [ { "version": "4.20", "status": "affected" }, { "version": "0", "lessThan": "4.20", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.189", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.158", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.112", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.54", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.8", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "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": "4.20", "versionEndExcluding": "6.1.189" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "6.6.158" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "6.12.112" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "6.18.54" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "7.2.8" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/4d8f7b1f586375df8bce23a0909566ad5e852259" }, { "url": "https://git.kernel.org/stable/c/e37fba1ba69385cff2d0e60b371ee19e7d1852d1" }, { "url": "https://git.kernel.org/stable/c/24b634852413229bb8340d908b115c3365f3a247" }, { "url": "https://git.kernel.org/stable/c/fbf69b7d0555ee83c871f58750770f74b7179ad1" }, { "url": "https://git.kernel.org/stable/c/ec2d7a52b3996ae81131617b4afc0af31583c1b4" }, { "url": "https://git.kernel.org/stable/c/51938dfa8a51a4f85328413fca9b6e21f9d2d088" } ], "title": "KVM: PPC: Book3S HV: fix use-after-free in kvmhv_emulate_tlbie_all_lpid()", "x_generator": { "engine": "bippy-1.2.0" } } } }