Vulnerability Name:

CVE-2021-28703 (CCN-213958)

Assigned:2021-11-23
Published:2021-11-23
Updated:2021-12-09
Summary: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.
CVSS v3 Severity:7.0 High (CVSS v3.1 Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H)
6.1 Medium (Temporal CVSS v3.1 Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C)
Exploitability Metrics:Attack Vector (AV): Local
Attack Complexity (AC): High
Privileges Required (PR): Low
User Interaction (UI): None
Scope:Scope (S): Unchanged
Impact Metrics:Confidentiality (C): High
Integrity (I): High
Availibility (A): High
9.3 Critical (CCN CVSS v3.1 Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H)
8.1 High (CCN Temporal CVSS v3.1 Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C)
Exploitability Metrics:Attack Vector (AV): Local
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope:Scope (S): Changed
Impact Metrics:Confidentiality (C): High
Integrity (I): High
Availibility (A): High
CVSS v2 Severity:6.9 Medium (CVSS v2 Vector: AV:L/AC:M/Au:N/C:C/I:C/A:C)
Exploitability Metrics:Access Vector (AV): Local
Access Complexity (AC): Medium
Authentication (Au): None
Impact Metrics:Confidentiality (C): Complete
Integrity (I): Complete
Availibility (A): Complete
7.2 High (CCN CVSS v2 Vector: AV:L/AC:L/Au:N/C:C/I:C/A:C)
Exploitability Metrics:Access Vector (AV): Local
Access Complexity (AC): Low
Athentication (Au): None
Impact Metrics:Confidentiality (C): Complete
Integrity (I): Complete
Availibility (A): Complete
Vulnerability Type:CWE-Other
Vulnerability Consequences:Gain Privileges
References:Source: MITRE
Type: CNA
CVE-2021-28703

Source: CCN
Type: Xen Security Advisory XSA-387
grant table v2 status pages may remain accessible after de-allocation (take

Source: XF
Type: UNKNOWN
xen-cve202128703-priv-esc(213958)

Source: MISC
Type: Vendor Advisory
https://xenbits.xenproject.org/xsa/advisory-387.txt

Vulnerable Configuration:Configuration 1:
  • cpe:/o:xen:xen:*:*:*:*:*:*:x86:* (Version < 14.4)

    • Configuration CCN 1:
  • cpe:/a:xensource:xen:4.0:*:*:*:*:*:*:*
  • OR cpe:/a:xensource:xen:4.1.1:*:*:*:*:*:*:*
  • OR cpe:/a:xensource:xen:4.1.2:*:*:*:*:*:*:*
  • OR cpe:/a:xensource:xen:4.1:*:*:*:*:*:*:*
  • OR cpe:/a:xensource:xen:4.2:*:*:*:*:*:*:*
  • OR cpe:/a:xensource:xen:4.0.0:*:*:*:*:*:*:*
  • OR cpe:/a:xensource:xen:3.4.0:*:*:*:*:*:*:*
  • OR cpe:/a:xensource:xen:4.4:*:*:*:*:*:*:*
  • OR cpe:/a:xensource:xen:4.5:*:*:*:*:*:*:*
  • OR cpe:/a:xensource:xen:4.6:*:*:*:*:*:*:*
  • OR cpe:/a:xensource:xen:4.7:*:*:*:*:*:*:*
  • OR cpe:/a:xensource:xen:4.8:*:*:*:*:*:*:*
  • OR cpe:/a:xensource:xen:4.9:*:*:*:*:*:*:*
  • OR cpe:/a:xensource:xen:4.10:*:*:*:*:*:*:*
  • OR cpe:/a:xensource:xen:4.11:*:*:*:*:*:*:*
  • OR cpe:/a:xensource:xen:4.12:*:*:*:*:*:*:*
  • OR cpe:/a:xensource:xen:4.12.3:*:*:*:*:*:*:*
  • OR cpe:/a:xensource:xen:4.12.4:*:*:*:*:*:*:*
  • OR cpe:/a:xensource:xen:4.10:*:*:*:*:*:*:*

    • * Denotes that component is vulnerable
    Oval Definitions
    Definition IDClassTitleLast Modified
    oval:org.opensuse.security:def:41886
    P
    		Security update for xen (Moderate)
    2021-12-01
    oval:org.opensuse.security:def:46316
    P
    		Security update for xen (Moderate)
    2021-12-01
    BACK
    xen xen *
    xensource xen 4.0
    xensource xen 4.1.1
    xensource xen 4.1.2
    xensource xen 4.1
    xensource xen 4.2
    xensource xen 4.0.0
    xensource xen 3.4.0
    xensource xen 4.4
    xensource xen 4.5
    xensource xen 4.6
    xensource xen 4.7
    xensource xen 4.8
    xensource xen 4.9
    xensource xen 4.10
    xensource xen 4.11
    xensource xen 4.12
    xensource xen 4.12.3
    xensource xen 4.12.4
    xensource xen 4.10