Vulnerability Name:

CVE-2020-29482 (CCN-193139)

Assigned:2020-12-15
Published:2020-12-15
Updated:2021-03-16
Summary:An issue was discovered in Xen through 4.14.x. A guest may access xenstore paths via absolute paths containing a full pathname, or via a relative path, which implicitly includes /local/domain/$DOMID for their own domain id. Management tools must access paths in guests' namespaces, necessarily using absolute paths. oxenstored imposes a pathname limit that is applied solely to the relative or absolute path specified by the client. Therefore, a guest can create paths in its own namespace which are too long for management tools to access. Depending on the toolstack in use, a malicious guest administrator might cause some management tools and debugging operations to fail. For example, a guest administrator can cause "xenstore-ls -r" to fail. However, a guest administrator cannot prevent the host administrator from tearing down the domain. 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:6.0 Medium (CVSS v3.1 Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H)
5.2 Medium (Temporal CVSS v3.1 Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H/E:U/RL:O/RC:C)
Exploitability Metrics:Attack Vector (AV): Local
Attack Complexity (AC): Low
Privileges Required (PR): High
User Interaction (UI): None
Scope:Scope (S): Changed
Impact Metrics:Confidentiality (C): None
Integrity (I): None
Availibility (A): High
6.2 Medium (CCN CVSS v3.1 Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
5.4 Medium (CCN Temporal CVSS v3.1 Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/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): None
Integrity (I): None
Availibility (A): High
CVSS v2 Severity:4.9 Medium (CVSS v2 Vector: AV:L/AC:L/Au:N/C:N/I:N/A:C)
Exploitability Metrics:Access Vector (AV): Local
Access Complexity (AC): Low
Authentication (Au): None
Impact Metrics:Confidentiality (C): None
Integrity (I): None
Availibility (A): Complete
4.9 Medium (CCN CVSS v2 Vector: AV:L/AC:L/Au:N/C:N/I:N/A:C)
Exploitability Metrics:Access Vector (AV): Local
Access Complexity (AC): Low
Athentication (Au): None
Impact Metrics:Confidentiality (C): None
Integrity (I): None
Availibility (A): Complete
Vulnerability Type:CWE-426
Vulnerability Consequences:Denial of Service
References:Source: MITRE
Type: CNA
CVE-2020-29482

Source: XF
Type: UNKNOWN
xen-cve202029482-dos(193139)

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

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

Source: DEBIAN
Type: Third Party Advisory
DSA-4812

Source: CCN
Type: Xen Security Advisory XSA-323
Xenstore: wrong path length check

Source: MISC
Type: Patch, Vendor Advisory
https://xenbits.xenproject.org/xsa/advisory-323.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 *