Vulnerability · Published Sep 23, 2020 · Assigned by mitre
CVE-2020-25598
Medium 5.5
In plain English
A medium-severity security flaw in the xen package (Alpine). There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 36% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
An issue was discovered in Xen 4.14.x. There is a missing unlock in the XENMEM_acquire_resource error path. The RCU (Read, Copy, Update) mechanism is a synchronisation primitive. A buggy error path in the XENMEM_acquire_resource exits without releasing an RCU reference, which is conceptually similar to forgetting to unlock a spinlock. A buggy or malicious HVM stubdomain can cause an RCU reference to be leaked. This causes subsequent administration operations, (e.g., CPU offline) to livelock, resulting in a host Denial of Service. The buggy codepath has been present since Xen 4.12. Xen 4.14 and later are vulnerable to the DoS. The side effects are believed to be benign on Xen 4.12 and 4.13, but patches are provided nevertheless. The vulnerability can generally only be exploited by x86 HVM VMs, as these are generally the only type of VM that have a Qemu stubdomain. x86 PV and PVH domains, as well as ARM VMs, typically don't use a stubdomain. Only VMs using HVM stubdomains can exploit the vulnerability. VMs using PV stubdomains, or with emulators running in dom0, cannot exploit the vulnerability.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.20 | xen | 4.14.0-r1 | ALPINE-CVE-2020-25598 |
| Alpine:v3.21 | xen | 4.14.0-r1 | ALPINE-CVE-2020-25598 |
| Alpine:v3.22 | xen | 4.14.0-r1 | ALPINE-CVE-2020-25598 |
| Alpine:v3.23 | xen | 4.14.0-r1 | ALPINE-CVE-2020-25598 |
| Alpine:v3.24 | xen | 4.14.0-r1 | ALPINE-CVE-2020-25598 |
Affected products (as reported)
References
- https://xenbits.xen.org/xsa/advisory-334.html x_refsource_MISC
- FEDORA-2020-306b84fd07 vendor-advisory, x_refsource_FEDORA
- FEDORA-2020-f668e579be vendor-advisory, x_refsource_FEDORA
- openSUSE-SU-2020:1608 vendor-advisory, x_refsource_SUSE
- FEDORA-2020-d46fe34349 vendor-advisory, x_refsource_FEDORA
- GLSA-202011-06 vendor-advisory, x_refsource_GENTOO