// For flags

CVE-2021-28701

Gentoo Linux Security Advisory 202208-23

Severity Score

7.8
*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

-
*SSVC
Descriptions

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.

Otra carrera en el manejo de la función XENMAPSPACE_grant_table de los Huéspedes, se les permite el acceso a determinadas páginas de memoria propiedad de Xen. La mayoría de estas páginas permanecen asignadas / asociadas a un huésped durante toda su vida. Las páginas de estado de la tabla Grant v2, sin embargo, se desasignan cuando un huésped cambia (de nuevo) de v2 a v1. Una liberación de dichas páginas requiere que el hipervisor haga cumplir que ninguna petición paralela pueda resultar en la adición de un mapeo de dicha página a un huésped. Esta aplicación no existía, permitiendo a los huéspedes mantener el acceso a las páginas liberadas y quizás reusarlas para otros fines. Desafortunadamente, cuando fue preparada la XSA-379, no se advirtió este problema similar

Multiple vulnerabilities have been discovered in Xen, the worst of which could result in remote code execution (guest sandbox escape). Versions less than 4.15.3 are affected.

*Credits: This issue was discovered by Julien Grall of Amazon.
CVSS Scores
Attack Vector
Local
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High
Attack Vector
Local
Attack Complexity
Medium
Authentication
None
Confidentiality
Partial
Integrity
Partial
Availability
Partial
* Common Vulnerability Scoring System
SSVC
  • Decision:-
Exploitation
-
Automatable
-
Tech. Impact
-
* Organization's Worst-case Scenario
Timeline
  • 2021-03-18 CVE Reserved
  • 2021-09-08 CVE Published
  • 2024-08-03 CVE Updated
  • 2025-03-30 EPSS Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
  • CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Xen
Search vendor "Xen"
 Xen
Search vendor "Xen" for product "Xen"
 >= 4.0.0
Search vendor "Xen" for product "Xen" and version " >= 4.0.0"
-
Affected
Debian
Search vendor "Debian"
 Debian Linux
Search vendor "Debian" for product "Debian Linux"
 11.0
Search vendor "Debian" for product "Debian Linux" and version "11.0"
-
Affected
Fedoraproject
Search vendor "Fedoraproject"
 Fedora
Search vendor "Fedoraproject" for product "Fedora"
 33
Search vendor "Fedoraproject" for product "Fedora" and version "33"
-
Affected
Fedoraproject
Search vendor "Fedoraproject"
 Fedora
Search vendor "Fedoraproject" for product "Fedora"
 34
Search vendor "Fedoraproject" for product "Fedora" and version "34"
-
Affected
Fedoraproject
Search vendor "Fedoraproject"
 Fedora
Search vendor "Fedoraproject" for product "Fedora"
 35
Search vendor "Fedoraproject" for product "Fedora" and version "35"
-
Affected