Vulnerability Details CVE-2021-28701
Another race in XENMAPSPACE_grant_table handling Guests are 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, are de-allocated when a guest switches (back) from v2 to v1. Freeing such pages requires that the hypervisor enforce that no parallel request can result in the addition of a mapping of such a page to a guest. That enforcement was missing, allowing guests to retain access to pages that were freed and perhaps re-used for other purposes. Unfortunately, when XSA-379 was being prepared, this similar issue was not noticed.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.0
EPSS Ranking 10.5%
CVSS Severity
CVSS v3 Score 7.8
CVSS v2 Score 4.4
Products affected by CVE-2021-28701
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cpe:2.3:o:debian:debian_linux:11.0
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cpe:2.3:o:fedoraproject:fedora:33
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cpe:2.3:o:fedoraproject:fedora:34
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cpe:2.3:o:fedoraproject:fedora:35
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cpe:2.3:o:xen:xen:4.1.6.1
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