CVE-2021-28706
First published: Wed Nov 24 2021(Updated: )
guests may exceed their designated memory limit When a guest is permitted to have close to 16TiB of memory, it may be able to issue hypercalls to increase its memory allocation beyond the administrator established limit. This is a result of a calculation done with 32-bit precision, which may overflow. It would then only be the overflowed (and hence small) number which gets compared against the established upper bound.
Credit: security@xen.org 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<4.12 | |
| Fedora | =34 | |
| Fedora | =35 | |
| Debian | =11.0 |
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Reference Links
- https://xenbits.xen.org/xsa/advisory-385.html
- https://security-tracker.debian.org/tracker/CVE-2021-28706
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/I7ZGWVVRI4XY2XSTBI3XEMWBXPDVX6OT/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/PXUI4VMD52CH3T7YXAG3J2JW7ZNN3SXF/
- https://www.debian.org/security/2021/dsa-5017
- https://xenbits.xenproject.org/xsa/advisory-385.txt
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/I7ZGWVVRI4XY2XSTBI3XEMWBXPDVX6OT/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PXUI4VMD52CH3T7YXAG3J2JW7ZNN3SXF/
- https://security.gentoo.org/glsa/202402-07
Frequently Asked Questions
What is the severity of CVE-2021-28706?
CVE-2021-28706 is considered a high-severity vulnerability due to the potential for guests to exceed their designated memory limits.
How do I fix CVE-2021-28706?
To fix CVE-2021-28706, update to the patched versions of Xen indicated in the advisory, specifically versions 4.14.6-1, 4.14.5+94-ge49571868d-1, 4.17.1+2-gb773c48e36-1, or 4.17.2+55-g0b56bed864-1.
What versions of Xen are affected by CVE-2021-28706?
CVE-2021-28706 affects Xen versions up to and including 4.12 and versions prior to 4.14.6-1.
Can CVE-2021-28706 be exploited remotely?
Yes, CVE-2021-28706 can potentially be exploited by malicious guests in a virtualized environment.
Is CVE-2021-28706 applicable to all operating systems?
No, CVE-2021-28706 specifically affects certain distributions like Debian and Fedora that utilize Xen hypervisor.
- collector/security-tracker-debian
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