{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-98061",
  "modified": "2026-10-07T14:35:31Z",
  "upstream": [
    "CVE-2026-98061"
  ],
  "published": "2026-09-25T10:24:31Z",
  "summary": "bpf: Reject tail calls directly from callback frames",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reject tail calls directly from callback frames\n\nA tail call from a non-zero frame is modeled as a return from that frame.\nThe verifier makes R0 unknown and calls prepare_func_exit() for the taken\nbranch.\n\nWhen the current frame is a synchronous callback, prepare_func_exit()\nenforces the callback return-value contract and marks R0 precise. Since the\ntail-call path synthesized R0 rather than deriving it from an instruction,\nprecision backtracking reaches the callback-calling instruction with R0\nstill requested and triggers the \"callback unexpected regs\" verifier bug.\nA CAP_BPF task can therefore cause a WARN and an -EFAULT BPF_PROG_LOAD.\n\nTail calls reachable from callbacks are already rejected later by\ncheck_max_stack_depth(). Reject a tail call made directly by a callback\nbefore constructing the inconsistent return state, using the existing\ndiagnostic. Tail calls from ordinary subprograms keep their current\nbehavior.",
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:13",
        "name": "linux"
      },
      "versions": [
        "1:6.18.29-1+rpt1",
        "1:6.18.33-1+rpt1",
        "1:6.18.34-1+rpt1",
        "1:6.18.39-1+rpt1",
        "1:6.18.50-1+rpt1"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.18.29+rpt-rpi-2712",
            "binary_version": "1:6.18.29-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.29+rpt-rpi-v6",
            "binary_version": "1:6.18.29-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.29+rpt-rpi-v7",
            "binary_version": "1:6.18.29-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.29+rpt-rpi-v8",
            "binary_version": "1:6.18.29-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.29+rpt-rpi-v8-rt",
            "binary_version": "1:6.18.29-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.33+rpt-rpi-2712",
            "binary_version": "1:6.18.33-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.33+rpt-rpi-v6",
            "binary_version": "1:6.18.33-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.33+rpt-rpi-v7",
            "binary_version": "1:6.18.33-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.33+rpt-rpi-v8",
            "binary_version": "1:6.18.33-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.33+rpt-rpi-v8-rt",
            "binary_version": "1:6.18.33-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.34+rpt-rpi-2712",
            "binary_version": "1:6.18.34-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.34+rpt-rpi-v6",
            "binary_version": "1:6.18.34-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.34+rpt-rpi-v7",
            "binary_version": "1:6.18.34-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.34+rpt-rpi-v8",
            "binary_version": "1:6.18.34-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.34+rpt-rpi-v8-rt",
            "binary_version": "1:6.18.34-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.39+rpt-rpi-2712",
            "binary_version": "1:6.18.39-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.39+rpt-rpi-v6",
            "binary_version": "1:6.18.39-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.39+rpt-rpi-v7",
            "binary_version": "1:6.18.39-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.39+rpt-rpi-v8",
            "binary_version": "1:6.18.39-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.39+rpt-rpi-v8-rt",
            "binary_version": "1:6.18.39-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.50+rpt-rpi-2712",
            "binary_version": "1:6.18.50-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.50+rpt-rpi-v6",
            "binary_version": "1:6.18.50-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.50+rpt-rpi-v7",
            "binary_version": "1:6.18.50-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.50+rpt-rpi-v8",
            "binary_version": "1:6.18.50-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.50+rpt-rpi-v8-rt",
            "binary_version": "1:6.18.50-1+rpt1"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.18.29-1+rpt1": {
            "linux_commit": "66318c5b5cd8145a662303af12ed39ac07eb27cc",
            "upstream_version": "6.18.29",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.18.53"
          },
          "1:6.18.33-1+rpt1": {
            "linux_commit": "95b85bebbedcaedfa7ca79116ed38b7376fba412",
            "upstream_version": "6.18.33",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.18.53"
          },
          "1:6.18.34-1+rpt1": {
            "linux_commit": "c8c7494100e99ee05b11aaa4f0588a223a63d1af",
            "upstream_version": "6.18.34",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.18.53"
          },
          "1:6.18.39-1+rpt1": {
            "linux_commit": "60ea684a8ace97bb0db1a16e20753bdd6ab371ff",
            "upstream_version": "6.18.39",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.18.53"
          },
          "1:6.18.50-1+rpt1": {
            "linux_commit": "cff533aec2fa601846766b32ff57204e0a61bed7",
            "upstream_version": "6.18.50",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.18.53"
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-98061"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/617c8266e49f45747f71e74177646a63f72b7025"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/96d31b28263c429a56e4de85bcf744a5c320b3a3"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/266aa4ad0b2e82397cd9045752c9bff03d98eddd"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-09-25T10:24:31Z"
  }
}