CVE-2021-28703

Name
CVE-2021-28703
Description
grant table v2 status pages may remain accessible after de-allocation (take two) Guest get permitted access to certain Xen-owned pages of memory. The majority of such pages remain allocated / associated with a guest for its entire lifetime. Grant table v2 status pages, however, get de-allocated when a guest switched (back) from v2 to v1. The freeing of such pages requires that the hypervisor know where in the guest these pages were mapped. The hypervisor tracks only one use within guest space, but racing requests from the guest to insert mappings of these pages may result in any of them to become mapped in multiple locations. Upon switching back from v2 to v1, the guest would then retain access to a page that was freed and perhaps re-used for other purposes. This bug was fortuitously fixed by code cleanup in Xen 4.14, and backported to security-supported Xen branches as a prerequisite of the fix for XSA-378.
NVD Severity
medium
Other trackers
Mailing lists
Exploits
Forges
GitHub (code, issues), Aports (code, issues)

References

Type URI
MISC https://xenbits.xenproject.org/xsa/advisory-387.txt

Match rules

CPE URI Source package Min version Max version
cpe:2.3:o:xen:xen:*:*:*:*:*:*:x86:* xen >= None < 14.4

Vulnerable and fixed packages

Source package Branch Version Maintainer Status
xen 3.12-main 4.13.4-r3 Natanael Copa <ncopa@alpinelinux.org> fixed
xen 3.16-main 4.16.1-r5 Natanael Copa <ncopa@alpinelinux.org> fixed
xen 3.15-main 4.15.3-r2 Natanael Copa <ncopa@alpinelinux.org> fixed
xen 3.14-main 4.15.3-r2 Natanael Copa <ncopa@alpinelinux.org> fixed
xen 3.13-main 4.14.5-r5 Natanael Copa <ncopa@alpinelinux.org> fixed
xen edge-main 4.16.2-r0 Natanael Copa <ncopa@alpinelinux.org> fixed