CVE-2021-28701
Description
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.
References
CvssV3 impact
BaseSeverity | HIGH |
ConfidentialityImpact | HIGH |
AttackComplexity | HIGH |
Scope | CHANGED |
AttackVector | LOCAL |
AvailabilityImpact | HIGH |
IntegrityImpact | HIGH |
PrivilegesRequired | LOW |
BaseScore | 7.8 |
VectorString | CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H |
Version | 3.1 |
UserInteraction | NONE |
CvssV2 impact
AccessComplexity | MEDIUM |
ConfidentialityImpact | PARTIAL |
AvailabilityImpact | PARTIAL |
IntegrityImpact | PARTIAL |
BaseScore | 4.4 |
VectorString | AV:L/AC:M/Au:N/C:P/I:P/A:P |
Version | 2.0 |
AccessVector | LOCAL |
Authentication | NONE |