CVE-2026-93147 (GCVE-0-2026-93147)

Vulnerability from cvelistv5 – Published: 2026-09-17 16:11 – Updated: 2026-09-18 17:56
VLAI
Title
s390/bpf: Replace ly instruction with llgf
Summary
In the Linux kernel, the following vulnerability has been resolved: s390/bpf: Replace ly instruction with llgf cpu_nr is a 32 bit value and BPF_REG_0 is a 64 bit register, when ly loads the cpu_nr into BPF_REG_0 it does not zero the upper bits, but llgf does.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 9012cf2491e3c5d28d098b0d6da804af82977032 , < 88500a86ab79f01c568de6ed00f5b1c5c79f11d5 (git)
Affected: 9012cf2491e3c5d28d098b0d6da804af82977032 , < 5f6cc299938b561cb01e343bab7042611fcee12a (git)
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Linux Linux Affected: 7.2
Unaffected: 0 , < 7.2 (semver)
Unaffected: 7.2.6 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/s390/net/bpf_jit_comp.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
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          "vendor": "Linux",
          "versions": [
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              "status": "affected",
              "version": "7.2"
            },
            {
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
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              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.6",
                  "versionStartIncluding": "7.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3-rc1",
                  "versionStartIncluding": "7.2",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ns390/bpf: Replace ly instruction with llgf\n\ncpu_nr is a 32 bit value and BPF_REG_0 is a 64 bit register, when ly loads\nthe cpu_nr into BPF_REG_0 it does not zero the upper bits, but llgf does."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "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 malformed input is eBPF bytecode containing BPF_JMP|BPF_CALL with imm=BPF_FUNC_get_smp_processor_id, loaded via bpf_prog_load() (bpf(2) BPF_PROG_LOAD). s390 bpf_jit_insn() then inlines that call as LY from get_lowcore()-\u003ecpu_nr; no remote protocol carries this bytecode.\nAC:L - The attacker sets BPF_REG_0 (s390 %r14) with BPF_LD_IMM64, then emits the helper call; bpf_jit_insn() always compiles it to LY (E358), which writes only bits 32-63 and leaves the attacker-chosen high half intact. bpf_opt_remove_dead_code() does not delete that store, and there is no race.\nPR:L - bpf_prog_load() allows BPF_PROG_TYPE_SOCKET_FILTER; sk_filter_func_proto() reaches bpf_base_func_proto(), which returns bpf_get_raw_smp_processor_id_proto for BPF_FUNC_get_smp_processor_id before its CAP_BPF gate, and BPF_MAP_TYPE_ARRAY is an unprivileged map. CAP_BPF is also granted by bpf_token_capable() in a delegated user namespace.\nUI:N - The attacker loads the crafted program with bpf(BPF_PROG_LOAD) and executes it themselves via BPF_PROG_TEST_RUN (sk_filter_prog_ops.test_run = bpf_prog_test_run_skb) or SO_ATTACH_BPF on their own socket; no other user must mount, open, or otherwise act.\nS:U - LY leaving stale high bits in BPF_REG_0 lets the JITed program read and write the host kernel through a verifier-approved PTR_TO_MAP_VALUE. That stays inside the same kernel authority; it is not a KVM guest-to-host or IOMMU bypass.\nC:H - do_refine_retval_range() sets R0\u2019s 64-bit range to [0, nr_cpu_ids-1] after BPF_FUNC_get_smp_processor_id, so check_map_access() allows adding it to a map-value pointer. LY preserves attacker high bits, so the subsequent BPF_LDX reads kernel memory far outside the map.\nI:H - The same forged pointer is a BPF_STX destination: the store lands at map_value + ((old_r0 \u0026 0xFFFFFFFF00000000) | cpu_nr). That is an attacker-controlled kernel write usable for corruption and control-flow hijack.\nA:H - Using that out-of-bounds map-value pointer (map_value plus the uncleared high 32 bits of %r14 after LY of cpu_nr) faults on unmapped addresses and oopses or panics the kernel."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-18T17:56:12.784Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/88500a86ab79f01c568de6ed00f5b1c5c79f11d5"
        },
        {
          "url": "https://git.kernel.org/stable/c/5f6cc299938b561cb01e343bab7042611fcee12a"
        }
      ],
      "title": "s390/bpf: Replace ly instruction with llgf",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-93147",
    "datePublished": "2026-09-17T16:11:44.793Z",
    "dateReserved": "2026-09-17T16:02:15.088Z",
    "dateUpdated": "2026-09-18T17:56:12.784Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-93147",
      "date": "2026-09-29",
      "epss": "0.00165",
      "percentile": "0.05098"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
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                "defaultStatus": "unaffected",
                "product": "Linux",
                "programFiles": [
                  "arch/s390/net/bpf_jit_comp.c"
                ],
                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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                "versions": [
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                    "status": "affected",
                    "version": "9012cf2491e3c5d28d098b0d6da804af82977032",
                    "versionType": "git"
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                    "versionType": "git"
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                "versions": [
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                    "version": "7.2.6",
                    "versionType": "semver"
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                    "version": "7.3-rc1",
                    "versionType": "original_commit_for_fix"
                  }
                ]
              }
            ],
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ns390/bpf: Replace ly instruction with llgf\n\ncpu_nr is a 32 bit value and BPF_REG_0 is a 64 bit register, when ly loads\nthe cpu_nr into BPF_REG_0 it does not zero the upper bits, but llgf does."
          }
        ],
        "id": "CVE-2026-93147",
        "lastModified": "2026-09-18T18:18:22.650",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "LOCAL",
                "availabilityImpact": "HIGH",
                "baseScore": 7.8,
                "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": "2026-09-17T17:18:09.867",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/5f6cc299938b561cb01e343bab7042611fcee12a"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/88500a86ab79f01c568de6ed00f5b1c5c79f11d5"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-22T16:24:03Z",
      "cve": "CVE-2026-93147",
      "id": "CVE-2026-93147",
      "initial_release_date": "2026-09-22T16:24:03Z",
      "product_status:known_not_affected": "347",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-93147",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-93147.json",
      "version": "2"
    }
  }
}



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