{
  "cveId": "CVE-2026-98049",
  "url": "https://patchblox.com/security/cve/CVE-2026-98049",
  "summary": "CVE-2026-98049 is fixed in linux on 1 platform, first by DEBIAN-CVE-2026-98049, released October 2, 2026. It is not reported as exploited. Patch Radar priority: Routine.",
  "title": "bpf: zero extend the result of an arena 32-bit cmpxchg",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  bpf: zero extend the result of an arena 32-bit cmpxchg  bpf_convert_ctx_accesses() rewrites an atomic on an arena pointer from BPF_STX | BPF_ATOMIC to BPF_STX | BPF_PROBE_ATOMIC, and it runs before bpf_opt_subreg_zext_lo32_rnd_hi32().  That pass emits an explicit zero extension for a 32-bit cmpxchg even when bpf_jit_needs_zext() is false. This is done because on some architectures 32-bit cmpxchg requires explicit zero extension for the dst register. E.g. on x86-64 \u0027lock cmpxchg\u0027 does not change the %eax if comparison is successful, while BPF semantics declare that each operation on a 32-bit register zero extends it\u0027s upper half.  is_cmpxchg_insn() matches BPF_MODE == BPF_ATOMIC only, so an arena cmpxchg misses said zero extension adjustment. This patch adjusts is_cmpxchg_insn() to match BPF_PROBE_ATOMIC alongside BPF_ATOMIC.",
  "published": "2026-09-25T11:17:33Z",
  "severity": "medium",
  "cvss": 5.5,
  "cvssVector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
  "cwe": "Incorrect Conversion between Numeric Types",
  "epss": 0.00155,
  "epssPercentile": 0.0464,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "vendorAdvisory": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-98049",
  "fixes": [
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "6.12.115-2",
      "fix": "DEBIAN-CVE-2026-98049",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-98049",
      "released": "2026-10-02T21:04:56Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "7.2.7-1",
      "fix": "DEBIAN-CVE-2026-98049",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-98049",
      "released": "2026-10-02T21:04:56Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T19:12:23Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}