Vulnerability · Published Aug 27, 2021 · Assigned by XEN
CVE-2021-28698
Medium 5.5
In plain English
A medium-severity security flaw in xen from Xen. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 28% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.20 | xen | 4.15.0-r2 | ALPINE-CVE-2021-28698 |
| Alpine:v3.21 | xen | 4.15.0-r2 | ALPINE-CVE-2021-28698 |
| Alpine:v3.22 | xen | 4.15.0-r2 | ALPINE-CVE-2021-28698 |
| Alpine:v3.23 | xen | 4.15.0-r2 | ALPINE-CVE-2021-28698 |
| Alpine:v3.24 | xen | 4.15.0-r2 | ALPINE-CVE-2021-28698 |
| Debian:12 | xen | 4.14.3-1 | DEBIAN-CVE-2021-28698 |
| Debian:13 | xen | 4.14.3-1 | DEBIAN-CVE-2021-28698 |
| Debian:14 | xen | 4.14.3-1 | DEBIAN-CVE-2021-28698 |
| Ubuntu:22.04:LTS | xen | no fix listed | UBUNTU-CVE-2021-28698 |
| Ubuntu:24.04:LTS | xen | no fix listed | UBUNTU-CVE-2021-28698 |
| Ubuntu:25.10 | xen | no fix listed | UBUNTU-CVE-2021-28698 |
| Ubuntu:26.04:LTS | xen | no fix listed | UBUNTU-CVE-2021-28698 |
| Ubuntu:26.10 | xen | no fix listed | UBUNTU-CVE-2021-28698 |
Affected products (as reported)
References
- https://xenbits.xenproject.org/xsa/advisory-380.txt x_refsource_MISC
- [oss-security] 20210901 Xen Security Advisory 380 v3 (CVE-2021-28698) - long running loops in grant table handling mailing-list, x_refsource_MLIST
- FEDORA-2021-4f129cc0c1 vendor-advisory, x_refsource_FEDORA
- FEDORA-2021-d68ed12e46 vendor-advisory, x_refsource_FEDORA
- DSA-4977 vendor-advisory, x_refsource_DEBIAN
- FEDORA-2021-081f9bf5d2 vendor-advisory, x_refsource_FEDORA
- GLSA-202208-23 vendor-advisory, x_refsource_GENTOO