{
  "cveId": "CVE-2025-38434",
  "url": "https://patchblox.com/security/cve/CVE-2025-38434",
  "summary": "CVE-2025-38434 is fixed in linux on 1 platform, first by DEBIAN-CVE-2025-38434, released July 25, 2025. It is not reported as exploited. Patch Radar priority: Routine.",
  "title": "linux: In the Linux kernel, the following vulnerability has been resolved:  Revert \u0022riscv: Define TASK_SIZE_MAX for __access...",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  Revert \u0022riscv: Define TASK_SIZE_MAX for __access_ok()\u0022  This reverts commit ad5643cf2f69 (\u0022riscv: Define TASK_SIZE_MAX for __access_ok()\u0022).  This commit changes TASK_SIZE_MAX to be LONG_MAX to optimize access_ok(), because the previous TASK_SIZE_MAX (default to TASK_SIZE) requires some computation.  The reasoning was that all user addresses are less than LONG_MAX, and all kernel addresses are greater than LONG_MAX. Therefore access_ok() can filter kernel addresses.  Addresses between TASK_SIZE and LONG_MAX are not valid user addresses, but access_ok() let them pass. That was thought to be okay, because they are not valid addresses at hardware level.  Unfortunately, one case is missed: get_user_pages_fast() happily accepts addresses between TASK_SIZE and LONG_MAX. futex(), for instance, uses get_user_pages_fast(). This causes the problem reported by Robert [1].  Therefore, revert this commit. TASK_SIZE_MAX is changed to the default: TASK_SIZE.  This unfortunately reduces performance, because TASK_SIZE is more expensive to compute compared to LONG_MAX. But correctness first, we can think about optimization later, if required.",
  "published": "2025-07-25T15:15:28Z",
  "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",
  "epss": 0.00202,
  "epssPercentile": 0.10275,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "6.12.37-1",
      "fix": "DEBIAN-CVE-2025-38434",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2025-38434",
      "released": "2025-07-25T15:15:28Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "6.12.37-1",
      "fix": "DEBIAN-CVE-2025-38434",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2025-38434",
      "released": "2025-07-25T15:15:28Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T06:59:42Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}