CVE-2021-28703 Affecting xen package, versions <4.15.1-r1
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Test your applications- Snyk ID SNYK-ALPINE320-XEN-7012437
- published 23 May 2024
- disclosed 7 Dec 2021
Introduced: 7 Dec 2021
CVE-2021-28703 Open this link in a new tabHow to fix?
Upgrade Alpine:3.20 xen to version 4.15.1-r1 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream xen package and not the xen package as distributed by Alpine.
See How to fix? for Alpine:3.20 relevant fixed versions and status.
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.