CVE-2020-25601

Description

An issue was discovered in Xen through 4.14.x. There is a lack of preemption in evtchn_reset() / evtchn_destroy(). In particular, the FIFO event channel model allows guests to have a large number of event channels active at a time. Closing all of these (when resetting all event channels or when cleaning up after the guest) may take extended periods of time. So far, there was no arrangement for preemption at suitable intervals, allowing a CPU to spend an almost unbounded amount of time in the processing of these operations. Malicious or buggy guest kernels can mount a Denial of Service (DoS) attack affecting the entire system. All Xen versions are vulnerable in principle. Whether versions 4.3 and older are vulnerable depends on underlying hardware characteristics.

How to fix CVE-2020-25601

To remediate CVE-2020-25601, upgrade the affected package to a fixed version below.

• —upgrade to 4.12.3-r4 or later
• —upgrade to 4.14.0+80-gd101b417b7-1 or later

Is CVE-2020-25601 being exploited?

Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.

Affected packages (2)

• from 0, < 4.12.3-r4
• from 0, < 4.14.0+80-gd101b417b7-1

CVSS scores

References (2)

• ADVISORYsecurity.alpinelinux.org/vuln/CVE-2020-25601
• ADVISORYsecurity-tracker.debian.org/tracker/CVE-2020-25601