{
  "id": "CVE-2021-28701",
  "sourceIdentifier": "security@xen.org",
  "published": "2021-09-08T14:15:08.547",
  "lastModified": "2022-10-28T16:20:05.017",
  "vulnStatus": "Analyzed",
  "descriptions": [
    {
      "lang": "en",
      "value": "Another race in XENMAPSPACE_grant_table handling Guests are permitted access to certain Xen-owned pages of memory. The majority of such pages remain allocated / associated with a guest for its entire lifetime. Grant table v2 status pages, however, are de-allocated when a guest switches (back) from v2 to v1. Freeing such pages requires that the hypervisor enforce that no parallel request can result in the addition of a mapping of such a page to a guest. That enforcement was missing, allowing guests to retain access to pages that were freed and perhaps re-used for other purposes. Unfortunately, when XSA-379 was being prepared, this similar issue was not noticed."
    },
    {
      "lang": "es",
      "value": "Otra carrera en el manejo de la funci\u00f3n XENMAPSPACE_grant_table de los Hu\u00e9spedes, se les permite el acceso a determinadas p\u00e1ginas de memoria propiedad de Xen. La mayor\u00eda de estas p\u00e1ginas permanecen asignadas / asociadas a un hu\u00e9sped durante toda su vida. Las p\u00e1ginas de estado de la tabla Grant v2, sin embargo, se desasignan cuando un hu\u00e9sped cambia (de nuevo) de v2 a v1. Una liberaci\u00f3n de dichas p\u00e1ginas requiere que el hipervisor haga cumplir que ninguna petici\u00f3n paralela pueda resultar en la adici\u00f3n de un mapeo de dicha p\u00e1gina a un hu\u00e9sped. Esta aplicaci\u00f3n no exist\u00eda, permitiendo a los hu\u00e9spedes mantener el acceso a las p\u00e1ginas liberadas y quiz\u00e1s reusarlas para otros fines. Desafortunadamente, cuando fue preparada la XSA-379, no se advirti\u00f3 este problema similar"
    }
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          "attackComplexity": "HIGH",
          "privilegesRequired": "LOW",
          "userInteraction": "NONE",
          "scope": "CHANGED",
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