Vulnerability Name:

CVE-2020-29479 (CCN-193142)

Assigned:2020-12-15
Published:2020-12-15
Updated:2022-04-26
Summary:An issue was discovered in Xen through 4.14.x. In the Ocaml xenstored implementation, the internal representation of the tree has special cases for the root node, because this node has no parent. Unfortunately, permissions were not checked for certain operations on the root node. Unprivileged guests can get and modify permissions, list, and delete the root node. (Deleting the whole xenstore tree is a host-wide denial of service.) Achieving xenstore write access is also possible. All systems using oxenstored are vulnerable. Building and using oxenstored is the default in the upstream Xen distribution, if the Ocaml compiler is available. Systems using C xenstored are not vulnerable.
CVSS v3 Severity:8.8 High (CVSS v3.1 Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H)
7.7 High (Temporal CVSS v3.1 Vector: CVSS:3.1/AV:L/AC:L/PR:L/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): Low
User Interaction (UI): None
Scope:Scope (S): Changed
Impact Metrics:Confidentiality (C): High
Integrity (I): High
Availibility (A): High
8.4 High (CCN CVSS v3.1 Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
7.3 High (CCN Temporal CVSS v3.1 Vector: CVSS:3.1/AV:L/AC:L/PR:N/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): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope:Scope (S): Unchanged
Impact Metrics:Confidentiality (C): High
Integrity (I): High
Availibility (A): High
CVSS v2 Severity:7.2 High (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
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-862
Vulnerability Consequences:Gain Privileges
References:Source: MITRE
Type: CNA
CVE-2020-29479

Source: XF
Type: UNKNOWN
xen-cve202029479-priv-esc(193142)

Source: FEDORA
Type: Mailing List, Third Party Advisory
FEDORA-2020-df772b417b

Source: FEDORA
Type: Mailing List, Third Party Advisory
FEDORA-2020-64859a826b

Source: GENTOO
Type: Third Party Advisory
GLSA-202107-30

Source: DEBIAN
Type: Third Party Advisory
DSA-4812

Source: CCN
Type: Xen Security Advisory XSA-353
oxenstored: permissions not checked on root node

Source: MISC
Type: Patch, Vendor Advisory
https://xenbits.xenproject.org/xsa/advisory-353.html

Vulnerable Configuration:Configuration 1:
  • cpe:/o:xen:xen:*:*:*:*:*:*:*:* (Version <= 4.14.0)

    • Configuration 2:
  • cpe:/o:debian:debian_linux:10.0:*:*:*:*:*:*:*

    • Configuration 3:
  • cpe:/o:fedoraproject:fedora:32:*:*:*:*:*:*:*
  • OR cpe:/o:fedoraproject:fedora:33:*:*:*:*:*:*:*

    • Configuration CCN 1:
  • cpe:/a:xensource:xen:*:*:*:*:*:*:*:*

    • * Denotes that component is vulnerable
    BACK
    xen xen *
    debian debian linux 10.0
    fedoraproject fedora 32
    fedoraproject fedora 33
    xensource xen *