CVE-2021-28698 Denial of service in xen
A malicious guest can cause a denial of service by triggering long-running loops in Xen's grant table handling, starving other domains or the hypervisor.
- 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-2021-28698?
CVE-2021-28698 is a medium-severity denial of service vulnerability in Debian Debian Linux, published on 27 Aug 2021. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
long running loops in grant table handling In order to properly monitor resource use, Xen maintains information on the grant mappings a domain may create to map grants offered by other domains. In the process of carrying out certain actions, Xen would iterate over all such entries, including ones which aren't in use anymore and some which may have been created but never used. If the number of entries for a given domain is large enough, this iterating of the entire table may tie up a CPU for too long, starving other domains or causing issues in the hypervisor itself. Note that a domain may map its own grants, i.e. there is no need for multiple domains to be involved here. A pair of "cooperating" guests may, however, cause the effects to be more severe.
Weakness: CWE-835
Which versions are affected by CVE-2021-28698?
It affects 3 products.
Products include Debian Debian Linux, Fedoraproject Fedora, Xen Xen.
How do I fix CVE-2021-28698?
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-2021-28698 being exploited?
There is no known exploitation of CVE-2021-28698 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as ALPINE-CVE-2021-28698, DEBIAN-CVE-2021-28698, GHSA-2g34-x978-mw32, UBUNTU-CVE-2021-28698.