CVE-2021-28705 - CVE House
Back to Database
Status published High CVE-2021-28705

issues with partially successful P2M updates on x86 T[his CNA...

Vulnerability Description

issues with partially successful P2M updates on x86 T[his CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities correspond to which CVE.] x86 HVM and PVH guests may be started in populate-on-demand (PoD) mode, to provide a way for them to later easily have more memory assigned. Guests are permitted to control certain P2M aspects of individual pages via hypercalls. These hypercalls may act on ranges of pages specified via page orders (resulting in a power-of-2 number of pages). In some cases the hypervisor carries out the requests by splitting them into smaller chunks. Error handling in certain PoD cases has been insufficient in that in particular partial success of some operations was not properly accounted for. There are two code paths affected - page removal (CVE-2021-28705) and insertion of new pages (CVE-2021-28709). (We provide one patch which combines the fix to both issues.)

Impact Analysis

Refer to official advisory for detailed impact metrics.

Remediation

Ensure systems are updated to the latest vendor-supplied patch levels.

THREAT MONITOR

Am I Vulnerable?

Launch our assessment wizard to check if your infrastructure is exposed to • CVE-2021-28705

Credits & Attribution

The following person or organization is credited with identifying this vulnerability, as recorded in the NVD database:

  • {'credit_data': {'description': {'description_data': [{'lang': 'eng', 'value': 'This issue was discovered by Jan Beulich of SUSE.'}]}}}

References

More from Xen

View All →
CVE-2025-58151
varstored: TOCTOU issues with mapped guest memory
Critical 9.4
CVE-2025-58150
x86: buffer overrun with shadow paging + tracing
Unknown 0
CVE-2025-58149
Incorrect removal of permissions on PCI device unplug
Unknown 0
CVE-2025-58148
x86: Incorrect input sanitisation in Viridian hypercalls
Unknown 0
CVE-2025-58147
x86: Incorrect input sanitisation in Viridian hypercalls
Unknown 0

Affected Vendor

Affected Software

xen
Vulnerable Versions:
4.14.x, 4.12.x, 4.15.x, xen-unstable, 4.13.x

Timeline

Official Publish: November 24th, 2021
Last Modified: August 3rd, 2024
Added to House: July 21st, 2026

CVSS Vectors

V3: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Weaknesses (CWE)

No CWE data available

MITRE ATT&CK TTPs

No associated TTPs found for this vulnerability.