Executive Summary

Informations
Name CVE-2019-18423 First vendor Publication 2019-10-31
Vendor Cve Last vendor Modification 2020-08-24

Security-Database Scoring CVSS v3

Cvss vector : CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Overall CVSS Score 8.8
Base Score 8.8 Environmental Score 8.8
impact SubScore 5.9 Temporal Score 8.8
Exploitabality Sub Score 2.8
 
Attack Vector Network Attack Complexity Low
Privileges Required Low User Interaction None
Scope Unchanged Confidentiality Impact High
Integrity Impact High Availability Impact High
Calculate full CVSS 3.0 Vectors scores

Security-Database Scoring CVSS v2

Cvss vector : (AV:N/AC:M/Au:S/C:C/I:C/A:C)
Cvss Base Score 8.5 Attack Range Network
Cvss Impact Score 10 Attack Complexity Medium
Cvss Expoit Score 6.8 Authentication Requires single instance
Calculate full CVSS 2.0 Vectors scores

Detail

An issue was discovered in Xen through 4.12.x allowing ARM guest OS users to cause a denial of service via a XENMEM_add_to_physmap hypercall. p2m->max_mapped_gfn is used by the functions p2m_resolve_translation_fault() and p2m_get_entry() to sanity check guest physical frame. The rest of the code in the two functions will assume that there is a valid root table and check that with BUG_ON(). The function p2m_get_root_pointer() will ignore the unused top bits of a guest physical frame. This means that the function p2m_set_entry() will alias the frame. However, p2m->max_mapped_gfn will be updated using the original frame. It would be possible to set p2m->max_mapped_gfn high enough to cover a frame that would lead p2m_get_root_pointer() to return NULL in p2m_get_entry() and p2m_resolve_translation_fault(). Additionally, the sanity check on p2m->max_mapped_gfn is off-by-one allowing "highest mapped + 1" to be considered valid. However, p2m_get_root_pointer() will return NULL. The problem could be triggered with a specially crafted hypercall XENMEM_add_to_physmap{, _batch} followed by an access to an address (via hypercall or direct access) that passes the sanity check but cause p2m_get_root_pointer() to return NULL. A malicious guest administrator may cause a hypervisor crash, resulting in a Denial of Service (DoS). Xen version 4.8 and newer are vulnerable. Only Arm systems are vulnerable. x86 systems are not affected.

Original Source

Url : http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-18423

CWE : Common Weakness Enumeration

% Id Name
100 % CWE-193 Off-by-one Error

CPE : Common Platform Enumeration

TypeDescriptionCount
Application 18
Os 196

Sources (Detail)

Source Url
BUGTRAQ https://seclists.org/bugtraq/2020/Jan/21
DEBIAN https://www.debian.org/security/2020/dsa-4602
FEDORA https://lists.fedoraproject.org/archives/list/package-announce@lists.fedorapr...
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedorapr...
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedorapr...
GENTOO https://security.gentoo.org/glsa/202003-56
MISC http://xenbits.xen.org/xsa/advisory-301.html
MLIST http://www.openwall.com/lists/oss-security/2019/10/31/4

Alert History

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0
1
Date Informations
2020-09-03 01:26:21
  • Multiple Updates
2020-05-23 02:26:59
  • First insertion