CVE-2026-98034 (GCVE-0-2026-98034)

Vulnerability from cvelistv5 – Published: 2026-09-25 10:23 – Updated: 2026-10-15 10:12
VLAI
Title
bpf: Mark NULL kptr stores precise
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: Mark NULL kptr stores precise check_map_kptr_access() permits a scalar store into an untrusted kptr field only when the register is known to contain zero. Unlike other verifier checks whose outcome depends on a scalar value, it does not mark that register precise. A state checkpoint reached with an imprecise zero can therefore prune a second path that reaches the store with an arbitrary nonzero scalar. The program can write attacker-controlled bits into the kptr field and load them back as a PTR_TO_BTF_ID. Call mark_chain_precision() before accepting a known-zero register. This forces state equivalence to compare its scalar range and makes the verifier visit and reject a path carrying a nonzero value.
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 7100 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 61df10c7799e27807ad5e459eec9d77cddf8bf45 , < bb667eb575c906f24c707986541a99424c5b07ea (git)
Affected: 61df10c7799e27807ad5e459eec9d77cddf8bf45 , < 86168208737bdd267d92d855d453d1d2f840df19 (git)
Affected: 61df10c7799e27807ad5e459eec9d77cddf8bf45 , < ecdc5043794c9184aa8e6c814603899479c46b35 (git)
Affected: b5a8069835e5236824a84281592d29f859b33153 (git)
Affected: 5.18.18 , < 5.19 (semver)
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Linux Linux Affected: 5.19
Unaffected: 0 , < 5.19 (semver)
Unaffected: 6.18.57 , ≤ 6.18.* (semver)
Unaffected: 7.2.7 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc2 , ≤ * (original_commit_for_fix)
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{
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          "product": "Linux",
          "programFiles": [
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          "vendor": "Linux",
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              "operator": "OR"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Mark NULL kptr stores precise\n\ncheck_map_kptr_access() permits a scalar store into an untrusted kptr\nfield only when the register is known to contain zero. Unlike other\nverifier checks whose outcome depends on a scalar value, it does not mark\nthat register precise.\n\nA state checkpoint reached with an imprecise zero can therefore prune a\nsecond path that reaches the store with an arbitrary nonzero scalar. The\nprogram can write attacker-controlled bits into the kptr field and load\nthem back as a PTR_TO_BTF_ID.\n\nCall mark_chain_precision() before accepting a known-zero register. This\nforces state equivalence to compare its scalar range and makes the verifier\nvisit and reject a path carrying a nonzero value."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-15T10:12:04.256Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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    "datePublished": "2026-09-25T10:23:49.352Z",
    "dateReserved": "2026-09-25T10:19:56.070Z",
    "dateUpdated": "2026-10-15T10:12:04.256Z",
    "state": "PUBLISHED"
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      "percentile": "0.05449"
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      "id": "msrc_CVE-2026-98034",
      "initial_release_date": "2026-09-28T00:01:12.000Z",
      "product_status:known_affected": "1",
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      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-98034.json",
      "version": "1"
    },
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Mark NULL kptr stores precise\n\ncheck_map_kptr_access() permits a scalar store into an untrusted kptr\nfield only when the register is known to contain zero. Unlike other\nverifier checks whose outcome depends on a scalar value, it does not mark\nthat register precise.\n\nA state checkpoint reached with an imprecise zero can therefore prune a\nsecond path that reaches the store with an arbitrary nonzero scalar. The\nprogram can write attacker-controlled bits into the kptr field and load\nthem back as a PTR_TO_BTF_ID.\n\nCall mark_chain_precision() before accepting a known-zero register. This\nforces state equivalence to compare its scalar range and makes the verifier\nvisit and reject a path carrying a nonzero value."
          }
        ],
        "id": "CVE-2026-98034",
        "lastModified": "2026-10-15T11:18:10.160",
        "metrics": {},
        "published": "2026-09-25T11:17:32.123",
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  }
}



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