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.

• CVE ID
• CVE-2021-28701

• Assigner
• security@xen.org

• Vulnerability Status
• Analyzed

• Published Version
• 2021-09-08T14:15:08

• Last Modified Date
• 2022-10-28T16:20:05

• Version
• 2.0

• Vector String
• AV:L/AC:M/Au:N/C:P/I:P/A:P

• Access Vector
• LOCAL

• Access Compatibility
• MEDIUM

• Authentication
• NONE

• Confidentiality Impact
• PARTIAL

• Integrity Impact
• PARTIAL

• Availability Impact
• PARTIAL

• Base Score
• 4.4

• Severity
• MEDIUM

• Exploitability Score
• 3.4

• Impact Score
• 6.4

• Version
• 3.1

• Vector String
• CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H

• Attack Vector
• LOCAL

• Attack Compatibility
• HIGH

• Privileges Required
• LOW

• User Interaction
• NONE

• Scope
• CHANGED

• Confidentiality Impact
• HIGH

• Availability Impact
• HIGH

• Base Score
• 7.8

• Base Severity
• HIGH

• Exploitability Score
• 1.1

• Impact Score
• 6