CVE-2026-63864 (GCVE-0-2026-63864)

Vulnerability from cvelistv5 – Published: 2026-07-19 14:04 – Updated: 2026-08-05 12:36
VLAI
Title
bpf: Propagate error from visit_tailcall_insn
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: Propagate error from visit_tailcall_insn Commit e40f5a6bf88a ("bpf: correct stack liveness for tail calls") added visit_tailcall_insn() but did not check its return value.
Severity
8.4 (High)
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6856 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: e40f5a6bf88a781d5f81bc6b8aab9ac31d8c98dd , < 945816e63c8677cf4bfde963a0774432ce8afc85 (git)
Affected: e40f5a6bf88a781d5f81bc6b8aab9ac31d8c98dd , < 6bd96e40f31dde8f8cd79772b4df0f171cf8a915 (git)
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Linux Linux Affected: 6.19
Unaffected: 0 , < 6.19 (semver)
Unaffected: 7.0.10 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
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  "containers": {
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          "product": "Linux",
          "programFiles": [
            "kernel/bpf/verifier.c"
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                  "vulnerable": true
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Propagate error from visit_tailcall_insn\n\nCommit e40f5a6bf88a (\"bpf: correct stack liveness for tail calls\") added\nvisit_tailcall_insn() but did not check its return value."
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
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              "lang": "en",
              "value": "AV:L - The bug is reached only through the bpf() syscall during BPF_PROG_LOAD verification (check_cfg/visit_insn), which is a local kernel interface per kernel CVSS guidance for BPF.\nAC:L - An attacker can craft a BPF program using tail calls and subprograms to hit visit_tailcall_insn(), and can pressure kernel memory (parallel BPF loads/maps) to make the small jt allocation fail while verification continues.\nPR:N - Exploitation occurs at BPF_PROG_LOAD time via bpf(); on systems with kernel.unprivileged_bpf_disabled=0, unprivileged users can load socket-filter programs with PROG_ARRAY maps and tail calls without CAP_BPF or root.\nUI:N - No victim interaction is required; the attacker triggers the flaw by loading a malicious BPF program through their own bpf() syscall.\nS:U - Impact is a BPF verifier bypass leading to kernel memory corruption and local privilege escalation within the same kernel security boundary, not a cross-authority escape such as VM guest-to-host.\nC:H - Incorrect tail-call stack liveness lets verifier-approved programs perform out-of-bounds stack reads at runtime, exposing adjacent kernel stack memory and enabling arbitrary kernel memory disclosure primitives.\nI:H - The verifier bypass permits out-of-bounds stack writes and type confusion on stack slots, which can be leveraged for control-flow hijacking and arbitrary kernel code execution from BPF context.\nA:H - Out-of-bounds BPF stack access can trigger kernel oops/panic during program execution, and repeated exploitation can be used for denial of service even when full exploitation is not attempted."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:36:40.261Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
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          "url": "https://git.kernel.org/stable/c/945816e63c8677cf4bfde963a0774432ce8afc85"
        },
        {
          "url": "https://git.kernel.org/stable/c/6bd96e40f31dde8f8cd79772b4df0f171cf8a915"
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-63864",
    "datePublished": "2026-07-19T14:04:50.605Z",
    "dateReserved": "2026-07-19T07:54:57.017Z",
    "dateUpdated": "2026-08-05T12:36:40.261Z",
    "state": "PUBLISHED"
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      "date": "2026-10-21",
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      "percentile": "0.07145"
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        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Propagate error from visit_tailcall_insn\n\nCommit e40f5a6bf88a (\"bpf: correct stack liveness for tail calls\") added\nvisit_tailcall_insn() but did not check its return value."
          }
        ],
        "id": "CVE-2026-63864",
        "lastModified": "2026-07-27T17:44:23.777",
        "metrics": {
          "cvssMetricV31": [
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                "attackVector": "LOCAL",
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                "baseScore": 8.4,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "NONE",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
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              "impactScore": 5.9,
              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
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        "published": "2026-07-19T15:16:53.303",
        "references": [
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            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/6bd96e40f31dde8f8cd79772b4df0f171cf8a915"
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        "vulnStatus": "Awaiting Analysis"
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      "current_release_date": "2026-07-22T07:06:12+00:00",
      "cve": "CVE-2026-63864",
      "id": "CVE-2026-63864",
      "initial_release_date": "2026-07-19T00:00:00+00:00",
      "product_status:known_affected": "76",
      "product_status:known_not_affected": "198",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: bpf: Propagate error from visit_tailcall_insn",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63864.json",
      "version": "3"
    }
  }
}



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