// For flags

CVE-2022-26362

Xen TLB Flush Bypass

Severity Score

6.4
*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

-
*SSVC
Descriptions

x86 pv: Race condition in typeref acquisition Xen maintains a type reference count for pages, in addition to a regular reference count. This scheme is used to maintain invariants required for Xen's safety, e.g. PV guests may not have direct writeable access to pagetables; updates need auditing by Xen. Unfortunately, the logic for acquiring a type reference has a race condition, whereby a safely TLB flush is issued too early and creates a window where the guest can re-establish the read/write mapping before writeability is prohibited.

x86 pv: Una condición de carrera en la adquisición de typeref Xen mantiene un recuento de referencias de tipo para las páginas, además de un recuento de referencias regular. Este esquema es usado para mantener invariantes requeridos para la seguridad de Xen, por ejemplo, los huéspedes PV no pueden tener acceso directo de escritura a las tablas de páginas; las actualizaciones necesitan ser auditadas por Xen. Desafortunadamente, la lógica para adquirir una referencia de tipo presenta una condición de carrera, por la cual un vaciado seguro de la TLB es emitido demasiado pronto y crea una ventana donde el huésped puede restablecer el mapeo de lectura/escritura antes de que sea prohibida la escritura

Xen's _get_page_type() contains an ABAC cmpxchg() race, where the code incorrectly assumes that if it reads a specific type_info value, and then later cmpxchg() succeeds, the type_info can't have changed in between.

*Credits: This issue was discovered by Jann Horn of Google Project Zero.
CVSS Scores
Attack Vector
Local
Attack Complexity
High
Privileges Required
High
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Attack Vector
Local
Attack Complexity
Medium
Authentication
None
Confidentiality
Complete
Integrity
Complete
Availability
Complete
* Common Vulnerability Scoring System
SSVC
  • Decision:-
Exploitation
-
Automatable
-
Tech. Impact
-
* Organization's Worst-case Scenario
Timeline
  • 2022-03-02 CVE Reserved
  • 2022-06-09 CVE Published
  • 2023-09-14 EPSS Updated
  • 2024-08-03 CVE 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"
*x86
Affected
Fedoraproject
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 Fedora
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 35
Search vendor "Fedoraproject" for product "Fedora" and version "35"
-
Affected
Fedoraproject
Search vendor "Fedoraproject"
 Fedora
Search vendor "Fedoraproject" for product "Fedora"
 36
Search vendor "Fedoraproject" for product "Fedora" and version "36"
-
Affected
Debian
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 Debian Linux
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 11.0
Search vendor "Debian" for product "Debian Linux" and version "11.0"
-
Affected