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CVE-2025-39793

Full vulnerability record from the local CVENow database.

Description

In the Linux kernel, the following vulnerability has been resolved: io_uring/memmap: cast nr_pages to size_t before shifting If the allocated size exceeds UINT_MAX, then it's necessary to cast the mr->nr_pages value to size_t to prevent it from overflowing. In practice this isn't much of a concern as the required memory size will have been validated upfront, and accounted to the user. And > 4GB sizes will be necessary to make the lack of a cast a problem, which greatly exceeds normal user locked_vm settings that are generally in the kb to mb range. However, if root is used, then accounting isn't done, and then it's possible to hit this issue.

Severity
HIGH
CVSS score
7.8 (v3.1)
Vulnerability status
Modified
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2025-09-12 16:15:33.590000
Last modified
2026-10-19 21:10:00.160000
View original CVE JSON 
{
  "id": "CVE-2025-39793",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2025-09-12T16:15:33.590",
  "lastModified": "2026-10-19T21:10:00.160",
  "vulnStatus": "Modified",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/memmap: cast nr_pages to size_t before shifting\n\nIf the allocated size exceeds UINT_MAX, then it's necessary to cast\nthe mr->nr_pages value to size_t to prevent it from overflowing. In\npractice this isn't much of a concern as the required memory size will\nhave been validated upfront, and accounted to the user. And > 4GB sizes\nwill be necessary to make the lack of a cast a problem, which greatly\nexceeds normal user locked_vm settings that are generally in the kb to\nmb range. However, if root is used, then accounting isn't done, and\nthen it's possible to hit this issue."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nio_uring/memmap: convertir nr_pages a size_t antes de desplazar\n\nSi el tamaño asignado excede UINT_MAX, entonces es necesario convertir el valor mr->nr_pages a size_t para evitar que desborde. En la práctica, esto no es motivo de gran preocupación, ya que el tamaño de memoria requerido habrá sido validado previamente y contabilizado al usuario. Y tamaños > 4GB serán necesarios para que la falta de una conversión sea un problema, lo que excede en gran medida la configuración normal de locked_vm del usuario, que generalmente está en el rango de kb a mb. Sin embargo, si se usa root, entonces la contabilidad no se realiza, y entonces es posible encontrarse con este problema."
    }
  ],
  "affected": [
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      "affectedData": [
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          "defaultStatus": "unaffected",
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              "versionType": "original_commit_for_fix",
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  "metrics": {
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          "attackVector": "LOCAL",
          "attackComplexity": "LOW",
          "privilegesRequired": "LOW",
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          "scope": "UNCHANGED",
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