TI-2021-09770 Aliases CVE-2021-28704 GHSA-gjrp-cpc9-h4r7

PoD operations on misaligned GFNs T[his CNA information record relates to multiple CVEs…

LOW 38Published 2021-11-24 · Updated 2024-08-03

Key facts

Attack vector: Local
Privileges required: Low
User interaction: None
Attack complexity: Low
Impact type: —
Confidentiality · integrity · availability: High · High · High
Fix status: Fixed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA.

Summary

PoD operations on misaligned GFNs 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). The implementation of some of these hypercalls for PoD does not enforce the base page frame number to be suitably aligned for the specified order, yet some code involved in PoD handling actually makes such an assumption. These operations are XENMEM_decrease_reservation (CVE-2021-28704) and XENMEM_populate_physmap (CVE-2021-28707), the latter usable only by domains controlling the guest, i.e. a de-privileged qemu or a stub domain. (Patch 1, combining the fix to both these two issues.) In addition handling of XENMEM_decrease_reservation can also trigger a host crash when the specified page order is neither 4k nor 2M nor 1G (CVE-2021-28708, patch 2).

Why it matters now

EPSS 0.00353 29th percentileScored 2026-11-07

Fix Fixed xen (Xen): next of 4.14.x

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
Xen	xen	xen-unstable	—	No fix listed	CNA
Xen	xen	4.12.x and later	next of 4.14.x	Patch available	CNA
Xen	xen	4.15.x	—	No fix listed	CNA

xen VendorXen Affected xen-unstable Fixed in — No fix listed CNA
xen VendorXen Affected 4.12.x and later Fixed in next of 4.14.x Patch available CNA
xen VendorXen Affected 4.15.x Fixed in — No fix listed CNA

CPE configurations NVD · 4

CPE	Versions	Role	Vendor
cpe:2.3:o:xen:xen:::::::x86:*	4.7.0 – 4.15.1	Vulnerable	Xen
cpe:2.3:o:fedoraproject:fedora:34:::::::*	34	Vulnerable	Fedoraproject
cpe:2.3:o:fedoraproject:fedora:35:::::::*	35	Vulnerable	Fedoraproject
cpe:2.3:o:debian:debian_linux:9.0:::::::*	9.0	Vulnerable	Debian

cpe:2.3:o:xen:xen:*:*:*:*:*:*:x86:* Versions 4.7.0 – 4.15.1 Vulnerable ·Xen
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:* Versions 34 Vulnerable ·Fedoraproject
cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:* Versions 35 Vulnerable ·Fedoraproject
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* Versions 9.0 Vulnerable ·Debian

Remediation

Fix · CNA xen (Xen) Fixed in next of 4.14.x

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

Advisory · 2021-11-21
xen — FEDORA-2021-03645e9807
7 records Highest priority Priority MEDIUM 2 MEDIUM, 5 LOW
Other records, highest priority first
- TI-2021-09772 Resource allocation without limits in xenPriority MEDIUM 42
- TI-2021-09774 PoD operations on misaligned GFNs T[his CNA information record relates to multiple CVEs…Priority MEDIUM 40
- TI-2021-09776 Improper privilege management in xenPriority LOW 38
Show all 7 records → Advisory →
Advisory · 2021-11-24
xen — FEDORA-2021-2b3a2de94f
6 records Highest priority Priority MEDIUM 2 MEDIUM, 4 LOW
Other records, highest priority first
- TI-2021-09772 Resource allocation without limits in xenPriority MEDIUM 42
- TI-2021-09774 PoD operations on misaligned GFNs T[his CNA information record relates to multiple CVEs…Priority MEDIUM 40
- TI-2021-09773 PoD operations on misaligned GFNs T[his CNA information record relates to multiple CVEs…Priority LOW 38
Show all 6 records → Advisory →

Timeline

2026-10-02 Threatist record created from CVE-2021-28704
2026-10-03 Alias added: GHSA-gjrp-cpc9-h4r7

References

Patch 1

https://xenbits.xenproject.org/xsa/advisory-388.txt

Advisory 4

TI-2012-00210 The x86-64 kernel system-call functionality in Xen 4.1.2 and earlier, as used in Citrix… CVSS 2.0HIGH 7.2
TI-2023-07042 Information disclosure through error messages in AMD Ryzen™ 3000 Series Desktop… CVSS 3.1MEDIUM 5.5
TI-2015-04333 The C+ mode offload emulation in the RTL8139 network card device model in QEMU, as used… CVSS 2.0HIGH 9.3
TI-2015-06741 The KVM subsystem in the Linux kernel through 4.2.6, and Xen 4.3.x through 4.6.x, allows… CVSS 3.1CRITICAL 10.0
TI-2018-06436 A statement in the System Programming Guide of the Intel 64 and IA-32 Architectures… CVSS 3.0HIGH 7.8
TI-2024-20522 x86: Incorrect logic for BTC/SRSO mitigations CVSS 3.1HIGH 7.5

See all 489 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences