CVE-2020-25603

Sažetak

An issue was discovered in Xen through 4.14.x. There are missing memory barriers when accessing/allocating an event channel. Event channels control structures can be accessed lockless as long as the port is considered to be valid. Such a sequence is missing an appropriate memory barrier (e.g., smp_*mb()) to prevent both the compiler and CPU from re-ordering access. A malicious guest may be able to cause a hypervisor crash resulting in a Denial of Service (DoS). Information leak and privilege escalation cannot be excluded. Systems running all versions of Xen are affected. Whether a system is vulnerable will depend on the CPU and compiler used to build Xen. For all systems, the presence and the scope of the vulnerability depend on the precise re-ordering performed by the compiler used to build Xen. We have not been able to survey compilers; consequently we cannot say which compiler(s) might produce vulnerable code (with which code generation options). GCC documentation clearly suggests that re-ordering is possible. Arm systems will also be vulnerable if the CPU is able to re-order memory access. Please consult your CPU vendor. x86 systems are only vulnerable if a compiler performs re-ordering.

Reference

CVSS

Base:	4.6
Impact:	6.4
Exploitability:	3.9

Pristup

Vektor	Složenost	Autentikacija
LOCAL	LOW	NONE

Impact

Povjerljivost	Cjelovitost	Dostupnost
PARTIAL	PARTIAL	PARTIAL

CVSS vektor

AV:L/AC:L/Au:N/C:P/I:P/A:P

Zadnje važnije ažuriranje

07-11-2023 - 03:20

Objavljeno

23-09-2020 - 22:15