CVE-2021-28698
First published: Fri Aug 27 2021(Updated: )
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.
Credit: security@xen.org
| Affected Software | Affected Version | How to fix |
|---|---|---|
| debian/xen | <=4.11.4+107-gef32c7afa2-1 | 4.14.6-1 4.14.5+94-ge49571868d-1 4.17.1+2-gb773c48e36-1 4.17.2+55-g0b56bed864-1 |
| Xen xen-unstable | >=3.2.0 | |
| Fedora | =33 | |
| Fedora | =34 | |
| Fedora | =35 | |
| Debian | =11.0 |
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Reference Links
- http://www.openwall.com/lists/oss-security/2021/09/01/2
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/2VQCFAPBNGBBAOMJZG6QBREOG5IIDZID/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/FZCNPSRPGFCQRYE2BI4D4Q4SCE56ANV2/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/LPRVHW4J4ZCPPOHZEWP5MOJT7XDGFFPJ/
- https://security.gentoo.org/glsa/202208-23
- https://www.debian.org/security/2021/dsa-4977
- https://xenbits.xenproject.org/xsa/advisory-380.txt
- https://xenbits.xen.org/xsa/advisory-380.html
- https://security-tracker.debian.org/tracker/CVE-2021-28698
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LPRVHW4J4ZCPPOHZEWP5MOJT7XDGFFPJ/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FZCNPSRPGFCQRYE2BI4D4Q4SCE56ANV2/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2VQCFAPBNGBBAOMJZG6QBREOG5IIDZID/
Frequently Asked Questions
What is the severity of CVE-2021-28698?
CVE-2021-28698 is classified as having a moderate severity due to the potential for denial-of-service through resource exhaustion.
How do I fix CVE-2021-28698?
To fix CVE-2021-28698, you should update your Xen software to a version that is not affected, such as those released after the vulnerability was disclosed.
Which software versions are affected by CVE-2021-28698?
CVE-2021-28698 affects Xen versions ranging from 3.2.0 up to 4.11.4+107-gef32c7afa2-1 for various distributions including Debian and Fedora.
What are the potential implications of CVE-2021-28698?
The implications of CVE-2021-28698 include the risk of prolonged denial-of-service attacks that could disrupt the availability of services running on affected systems.
Is CVE-2021-28698 present in Xen hypervisor environments?
Yes, CVE-2021-28698 is specifically related to long-running loops in grant table handling within Xen hypervisor environments.
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