Vulnerability in Xen
CVE-2021-28698
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.
EPSS: 0.004 (27.7th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
Affected products
- Xen — versions 4.14.x, unspecified, 4.15.x
- Debian Debian_linux — versions 11.0
- Fedoraproject Fedora — versions 33, 34, 35
Weakness classification (CWE)
Public proof-of-concept exploits
References
- security@xen.org (x_refsource_MISC, Vendor Advisory)
- security@xen.org (mailing-list, x_refsource_MLIST, Mailing List, Third Party Advisory)
- security@xen.org (x_refsource_FEDORA, vendor-advisory)
- security@xen.org (x_refsource_FEDORA, vendor-advisory)
- security@xen.org (vendor-advisory, Third Party Advisory, x_refsource_DEBIAN)
- security@xen.org (x_refsource_FEDORA, vendor-advisory)
- security@xen.org (vendor-advisory, Third Party Advisory, x_refsource_GENTOO)
Frequently asked questions
- What is CVE-2021-28698?
- CVE-2021-28698 is a medium-severity vulnerability in Xen, classified under Loop with Unreachable Exit Condition (Infinite Loop). CVSS score: 5.5/10. Published 2021-08-27.
- How severe is CVE-2021-28698?
- Medium severity. CVSS v3 base score is 5.5 out of 10.
- Is CVE-2021-28698 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.