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CVE-2025-38733

Full vulnerability record from the local CVENow database.

Description

In the Linux kernel, the following vulnerability has been resolved: s390/mm: Do not map lowcore with identity mapping Since the identity mapping is pinned to address zero the lowcore is always also mapped to address zero, this happens regardless of the relocate_lowcore command line option. If the option is specified the lowcore is mapped twice, instead of only once. This means that NULL pointer accesses will succeed instead of causing an exception (low address protection still applies, but covers only parts). To fix this never map the first two pages of physical memory with the identity mapping.

Severity
MEDIUM
CVSS score
5.5 (v3.1)
Vulnerability status
Modified
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2025-09-05 18:15:42.550000
Last modified
2026-10-19 21:10:00.160000
View original CVE JSON 
{
  "id": "CVE-2025-38733",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2025-09-05T18:15:42.550",
  "lastModified": "2026-10-19T21:10:00.160",
  "vulnStatus": "Modified",
  "cveTags": [],
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    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ns390/mm: Do not map lowcore with identity mapping\n\nSince the identity mapping is pinned to address zero the lowcore is always\nalso mapped to address zero, this happens regardless of the relocate_lowcore\ncommand line option. If the option is specified the lowcore is mapped\ntwice, instead of only once.\n\nThis means that NULL pointer accesses will succeed instead of causing an\nexception (low address protection still applies, but covers only parts).\nTo fix this never map the first two pages of physical memory with the\nidentity mapping."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\ns390/mm: No mapear lowcore con mapeo de identidad\n\nDado que el mapeo de identidad está anclado a la dirección cero, el lowcore siempre también se mapea a la dirección cero, esto ocurre independientemente de la opción de línea de comandos relocate_lowcore. Si la opción se especifica, el lowcore se mapea dos veces, en lugar de solo una vez.\n\nEsto significa que los accesos a punteros NULL tendrán éxito en lugar de causar una excepción (la protección de direcciones bajas aún se aplica, pero cubre solo partes). Para solucionar esto, nunca mapear las primeras dos páginas de memoria física con el mapeo de identidad."
    }
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