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CVE-2021-28706

29
FAUCET Score

CVE-2021-28706 is a high-severity vulnerability affecting Xen hypervisors, Debian, and Fedora, where a guest virtual machine can exceed its allocated memory limit. This occurs due to a 32-bit precision overflow in memory allocation calculations, allowing the guest to bypass established upper bounds. With a CVSS score of 8.6, this vulnerability is network-exploitable with low attack complexity, leading to a high availability impact on the host system. There is currently no public exploit code available, no evidence of active exploitation, and minimal community discussion or media coverage surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
>= 3.2, < 4.12CPE matchmatch criteria
cpe:2.3:o:xen:xen:*:*:*:*:*:*:*:*
34CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
35CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*
11.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.6HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
4.0
CvssVersion
3.1

Exploit Intelligence

EPSS Score
2.06%
Probability of exploitation in next 30 days
EPSS Percentile
79.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0206 is in the 64th percentile among its peer group of 51,553 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/I7ZGWVVRI4XY2XSTBI3XEMWBXPDVX6OT
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/PXUI4VMD52CH3T7YXAG3J2JW7ZNN3SXF
security.gentoo.org / glsa/202402-07
debian.org / security/2021/dsa-5017
Third Party Advisory
xenbits.xenproject.org / xsa/advisory-385.txt
MitigationPatchThird Party Advisory