4.6 Medium
CVSS2
Attack Vector
LOCAL
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:L/AC:L/Au:N/C:P/I:P/A:P
7.8 High
CVSS3
Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
0.0004 Low
EPSS
Percentile
14.2%
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.
Author | Note |
---|---|
mdeslaur | hypervisor packages are in universe. For issues in the hypervisor, add appropriate tags to each section, ex: Tags_xen: universe-binary |
launchpad.net/bugs/cve/CVE-2020-25603
lists.fedoraproject.org/archives/list/[email protected]/message/4JRXMKEMQRQYWYEPHVBIWUEAVQ3LU4FN/
nvd.nist.gov/vuln/detail/CVE-2020-25603
security-tracker.debian.org/tracker/CVE-2020-25603
ubuntu.com/security/notices/USN-5617-1
www.cve.org/CVERecord?id=CVE-2020-25603
xenbits.xen.org/xsa/advisory-340.html
4.6 Medium
CVSS2
Attack Vector
LOCAL
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:L/AC:L/Au:N/C:P/I:P/A:P
7.8 High
CVSS3
Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
0.0004 Low
EPSS
Percentile
14.2%