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CVE-2021-28705

26
FAUCET Score

CVE-2021-28705 is a high-severity vulnerability (CVSS 7.8) affecting Xen hypervisors, specifically impacting x86 HVM and PVH guests running on Debian and Fedora. It stems from insufficient error handling during page removal operations in populate-on-demand (PoD) mode, where partial success of memory operations is not properly accounted for. This local vulnerability allows an attacker with low privileges to achieve high impact on confidentiality, integrity, and availability. There is currently no known active exploitation, public exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
>= 3.4.0, <= 4.12.4CPE matchmatch criteria
cpe:2.3:o:xen:xen:*:*:*:*:*:*:x86:*
>= 4.13.0, <= 4.13.4CPE matchmatch criteria
cpe:2.3:o:xen:xen:*:*:*:*:*:*:x86:*
>= 4.14.0, <= 4.14.3CPE matchmatch criteria
cpe:2.3:o:xen:xen:*:*:*:*:*:*:x86:*
4.15.0CPE matchmatch criteria
cpe:2.3:o:xen:xen:4.15.0:*:*:*:*:*:x86:*
4.15.1CPE matchmatch criteria
cpe:2.3:o:xen:xen:4.15.1:*:*:*:*:*:x86:*

CVSS Data

CVSS version used by this source: 3.1

7.8HIGH

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

Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
1.8
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.33%
Probability of exploitation in next 30 days
EPSS Percentile
25.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0033 is in the 64th percentile among its peer group of 17,070 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.2 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 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-389.txt
PatchVendor Advisory