Vulnerability · Published Nov 24, 2021 · Assigned by XEN
CVE-2021-28705
High 7.8
In plain English
A high-severity security flaw in xen from Xen. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 30% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.)
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.20 | xen | 4.15.1-r2 | ALPINE-CVE-2021-28705 |
| Alpine:v3.21 | xen | 4.15.1-r2 | ALPINE-CVE-2021-28705 |
| Alpine:v3.22 | xen | 4.15.1-r2 | ALPINE-CVE-2021-28705 |
| Alpine:v3.23 | xen | 4.15.1-r2 | ALPINE-CVE-2021-28705 |
| Alpine:v3.24 | xen | 4.15.1-r2 | ALPINE-CVE-2021-28705 |
| Debian:12 | xen | 4.14.3+32-g9de3671772-1 | DEBIAN-CVE-2021-28705 |
| Debian:13 | xen | 4.14.3+32-g9de3671772-1 | DEBIAN-CVE-2021-28705 |
| Debian:14 | xen | 4.14.3+32-g9de3671772-1 | DEBIAN-CVE-2021-28705 |
| Ubuntu:22.04:LTS | xen | no fix listed | UBUNTU-CVE-2021-28705 |
| Ubuntu:24.04:LTS | xen | no fix listed | UBUNTU-CVE-2021-28705 |
| Ubuntu:25.10 | xen | no fix listed | UBUNTU-CVE-2021-28705 |
| Ubuntu:26.04:LTS | xen | no fix listed | UBUNTU-CVE-2021-28705 |
| Ubuntu:26.10 | xen | no fix listed | UBUNTU-CVE-2021-28705 |
Affected products (as reported)
References
- https://xenbits.xenproject.org/xsa/advisory-389.txt
- FEDORA-2021-03645e9807 vendor-advisory
- DSA-5017 vendor-advisory
- FEDORA-2021-2b3a2de94f vendor-advisory
- GLSA-202402-07 vendor-advisory