CVE-2026-98376 (GCVE-0-2026-98376)

Vulnerability from cvelistv5 – Published: 2026-10-09 07:34 – Updated: 2026-10-24 14:08
VLAI
Title
bpf: Use array_map_meta_equal for percpu array inner map replacement
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: Use array_map_meta_equal for percpu array inner map replacement percpu_array_map_ops.map_meta_equal points to the generic bpf_map_meta_equal(), which does not compare max_entries. When a percpu array serves as an inner map, replacing it with one that has fewer max_entries bypasses the check. Since percpu_array_map_gen_lookup() inlines the original template's index_mask as a JIT immediate, a lookup on the replacement map can access pptrs[] out of bounds. Point percpu_array_map_ops.map_meta_equal to array_map_meta_equal(), which already enforces the max_entries equality check. Add a selftest to verify that replacing a percpu array inner map with a differently-sized one is rejected.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6649 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: db69718b8efac802c7cc20d5a6c7dfc913f99c43 , < 593980175389a05793f6060aa20e626330960395 (git)
guessed Create a notification for this product.
Linux Linux Affected: 6.10
Unaffected: 0 , < 6.10 (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/arraymap.c",
            "tools/testing/selftests/bpf/prog_tests/percpu_array_inner_map.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "593980175389a05793f6060aa20e626330960395",
              "status": "affected",
              "version": "db69718b8efac802c7cc20d5a6c7dfc913f99c43",
              "versionType": "git"
            }
          ]
        },
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          "product": "Linux",
          "programFiles": [
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            "tools/testing/selftests/bpf/prog_tests/percpu_array_inner_map.c"
          ],
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          "vendor": "Linux",
          "versions": [
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
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              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1",
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Use array_map_meta_equal for percpu array inner map replacement\n\npercpu_array_map_ops.map_meta_equal points to the generic\nbpf_map_meta_equal(), which does not compare max_entries.  When a\npercpu array serves as an inner map, replacing it with one that has\nfewer max_entries bypasses the check.  Since percpu_array_map_gen_lookup()\ninlines the original template\u0027s index_mask as a JIT immediate, a lookup\non the replacement map can access pptrs[] out of bounds.\n\nPoint percpu_array_map_ops.map_meta_equal to array_map_meta_equal(),\nwhich already enforces the max_entries equality check.\n\nAdd a selftest to verify that replacing a percpu array inner map with\na differently-sized one is rejected."
        }
      ],
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The local bpf(BPF_MAP_UPDATE_ELEM) path reaches map_update_elem()-\u003ebpf_map_update_value()-\u003ebpf_fd_array_map_update_elem()-\u003ebpf_map_fd_get_ptr(), where the patched percpu_array_map_ops.map_meta_equal validates the replacement map; no network handler supplies its FD or dimensions.\nAC:L - The attacker chooses the template and replacement max_entries, lookup key, program, and trigger; an index below the template limit but beyond the replacement deterministically reads pptrs[] out of bounds. No race or other actor is required on a JIT-enabled x86-64 or arm64 target.\nPR:L - map_create() places PERCPU_ARRAY and ARRAY_OF_MAPS in its unprivileged branch, and bpf_prog_load() permits SOCKET_FILTER without CAP_BPF when unprivileged BPF is enabled; alternatively, a user-namespace BPF token satisfies the gates without init-namespace root.\nUI:N - The attacker creates and replaces the maps, loads the lookup program, attaches it through SO_ATTACH_BPF to their own socket, and sends the triggering data themselves; no victim action is needed.\nS:U - percpu_array_map_gen_lookup() converts the out-of-bounds pptrs[] slot into a pointer used against the same host kernel\u0027s memory; this is ordinary kernel privilege escalation, not a guest-to-host, IOMMU, or other security-authority crossing.\nC:H - percpu_array_map_gen_lookup() loads a 64-bit pptrs[index] out of bounds and returns its adjusted value as a verifier-trusted map-value pointer. Because bpf_map_area_alloc() kmallocs the flexible object, map spraying can place chosen bytes at that slot, enabling kernel reads copied into another map.\nI:H - The forged PTR_TO_MAP_VALUE is writable because default map flags grant BPF_MAP_CAN_WRITE; direct BPF stores through an attacker-groomed out-of-bounds pptrs[] value therefore provide an arbitrary kernel-write primitive suitable for control-flow hijacking.\nA:H - Without successful grooming, BPF_MOV64_PERCPU_REG adjusts the garbage pointer loaded beyond pptrs[] and the attacker\u0027s next value access dereferences it, causing a kernel oops or panic; the attacker can repeatedly run the same socket-filter program."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-24T14:08:36.004Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/593980175389a05793f6060aa20e626330960395"
        }
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      "title": "bpf: Use array_map_meta_equal for percpu array inner map replacement",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98376",
    "datePublished": "2026-10-09T07:34:17.043Z",
    "dateReserved": "2026-09-25T10:25:14.345Z",
    "dateUpdated": "2026-10-24T14:08:36.004Z",
    "state": "PUBLISHED"
  },
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  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
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      "date": "2026-11-04",
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      "percentile": "0.04981"
    },
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      "cve": "CVE-2026-98376",
      "id": "msrc_CVE-2026-98376",
      "initial_release_date": "2026-10-20T22:23:54.000Z",
      "product_status:under_investigation": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "bpf: Use array_map_meta_equal for percpu array inner map replacement",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-98376.json",
      "version": "2"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
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                "product": "Linux",
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            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Use array_map_meta_equal for percpu array inner map replacement\n\npercpu_array_map_ops.map_meta_equal points to the generic\nbpf_map_meta_equal(), which does not compare max_entries.  When a\npercpu array serves as an inner map, replacing it with one that has\nfewer max_entries bypasses the check.  Since percpu_array_map_gen_lookup()\ninlines the original template\u0027s index_mask as a JIT immediate, a lookup\non the replacement map can access pptrs[] out of bounds.\n\nPoint percpu_array_map_ops.map_meta_equal to array_map_meta_equal(),\nwhich already enforces the max_entries equality check.\n\nAdd a selftest to verify that replacing a percpu array inner map with\na differently-sized one is rejected."
          }
        ],
        "id": "CVE-2026-98376",
        "lastModified": "2026-10-24T14:16:39.733",
        "metrics": {
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                "attackVector": "LOCAL",
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                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
                "version": "3.1"
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              "impactScore": 5.9,
              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
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        "published": "2026-10-09T08:16:55.910",
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            "url": "https://git.kernel.org/stable/c/593980175389a05793f6060aa20e626330960395"
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
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      "current_release_date": "2026-10-24T14:22:37+00:00",
      "cve": "CVE-2026-98376",
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      "product_status:known_affected": "185",
      "product_status:known_not_affected": "93",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: bpf: Use array_map_meta_equal for percpu array inner map replacement",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98376.json",
      "version": "3"
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      "status": "interim",
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      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/2026/cve-2026-98376.json",
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}



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