CVE-2025-37996 (GCVE-0-2025-37996)
Vulnerability from cvelistv5
Published
2025-05-29 13:15
Modified
2026-08-05 11:58
Severity ?
8.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Fix uninitialized memcache pointer in user_mem_abort() Commit fce886a60207 ("KVM: arm64: Plumb the pKVM MMU in KVM") made the initialization of the local memcache variable in user_mem_abort() conditional, leaving a codepath where it is used uninitialized via kvm_pgtable_stage2_map(). This can fail on any path that requires a stage-2 allocation without transition via a permission fault or dirty logging. Fix this by making sure that memcache is always valid.
References
Impacted products
Vendor Product Version
Linux Linux Version: fce886a6020734d6253c2c5a3bc285e385cc5496
Version: fce886a6020734d6253c2c5a3bc285e385cc5496
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/arm64/kvm/mmu.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "a26d50f8a4a5049e956984797b5d0dedea4bbb18",
              "status": "affected",
              "version": "fce886a6020734d6253c2c5a3bc285e385cc5496",
              "versionType": "git"
            },
            {
              "lessThan": "157dbc4a321f5bb6f8b6c724d12ba720a90f1a7c",
              "status": "affected",
              "version": "fce886a6020734d6253c2c5a3bc285e385cc5496",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "arch/arm64/kvm/mmu.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.14"
            },
            {
              "lessThan": "6.14",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.14.*",
              "status": "unaffected",
              "version": "6.14.7",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.15",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.14.7",
                  "versionStartIncluding": "6.14",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.15",
                  "versionStartIncluding": "6.14",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: arm64: Fix uninitialized memcache pointer in user_mem_abort()\n\nCommit fce886a60207 (\"KVM: arm64: Plumb the pKVM MMU in KVM\") made the\ninitialization of the local memcache variable in user_mem_abort()\nconditional, leaving a codepath where it is used uninitialized via\nkvm_pgtable_stage2_map().\n\nThis can fail on any path that requires a stage-2 allocation\nwithout transition via a permission fault or dirty logging.\n\nFix this by making sure that memcache is always valid."
        }
      ],
      "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 vulnerable code is the host kernel\u0027s stage-2 fault handler, reached through guest execution under KVM_RUN (or directly by a local user with /dev/kvm who builds their own VM); there is no network-facing path.\nAC:L - No race or unpredictable precondition is involved \u2014 an attacker controlling a guest can deterministically arrange a huge-block stage-2 mapping and then take a non-write permission fault (instruction fetch, or an NV shadow-S2 granule mismatch) so that `memcache` is consumed uninitialized on every attempt.\nPR:L - The attacker only needs code execution inside a guest VM, or unprivileged access to /dev/kvm on the host (commonly group- or world-accessible on Android, desktops and libvirt hosts); no host root is required.\nUI:N - The fault is raised by the guest\u0027s own memory access during normal vCPU execution, with no action needed from the host operator or any other user.\nS:C - The bug lets a guest corrupt host-kernel memory through the stage-2 page-table allocator, crossing from the VM\u0027s security authority into the hypervisor host \u2014 a guest-to-host boundary violation.\nC:H - `kvm_mmu_memory_cache_alloc()` performs `mc-\u003eobjects[--mc-\u003enobjs]` through the garbage pointer, an attacker-influenceable arbitrary read whose result is then mapped into the guest\u0027s stage-2 tables, exposing host memory contents to the guest.\nI:H - The uninitialized pointer yields wild writes (`--mc-\u003enobjs`, and under pKVM `swap(mapping, cache-\u003emapping)` followed by `mapping-\u003egfn/pfn` stores) and causes arbitrary host memory to be installed as a guest stage-2 page table with matching `get_page`/`put_page` refcount manipulation \u2014 a host memory-corruption and control-flow-hijack primitive.\nA:H - In the ordinary case the wild dereference (or the `BUG_ON(!p)` in `kvm_mmu_memory_cache_alloc()`) oopses in the vCPU thread while holding the KVM fault lock, panicking the host kernel and taking down every VM on the machine."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T11:58:48.143Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/a26d50f8a4a5049e956984797b5d0dedea4bbb18"
        },
        {
          "url": "https://git.kernel.org/stable/c/157dbc4a321f5bb6f8b6c724d12ba720a90f1a7c"
        }
      ],
      "title": "KVM: arm64: Fix uninitialized memcache pointer in user_mem_abort()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-37996",
    "datePublished": "2025-05-29T13:15:54.956Z",
    "dateReserved": "2025-04-16T04:51:23.976Z",
    "dateUpdated": "2026-08-05T11:58:48.143Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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