CVE-2020-25598 Denial of service in n/a
A malicious HVM stubdomain can leak RCU references, causing host livelock and denial of service during administration operations.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2020-25598?
CVE-2020-25598 is a medium-severity denial of service vulnerability in Fedoraproject Fedora, published on 23 Sep 2020. It can only be exploited from the same machine or local network, with no action from the victim.
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.
Weakness: CWE-670
Which versions are affected by CVE-2020-25598?
It affects 3 products.
Products include Fedoraproject Fedora, Opensuse Leap, Xen Xen.
How do I fix CVE-2020-25598?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2020-25598 being exploited?
There is no known exploitation of CVE-2020-25598 in the wild and no public exploit code.
Other vulnerabilities in Fedoraproject Fedora
Sources
Also known as ALPINE-CVE-2020-25598, GHSA-6vvr-9x9v-68j4.