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Vulnerability Details : CVE-2019-18423

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.
Publish Date : 2019-10-31 Last Update Date : 2020-08-24
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- CVSS Scores & Vulnerability Types

CVSS Score
8.5
Confidentiality Impact Complete (There is total information disclosure, resulting in all system files being revealed.)
Integrity Impact Complete (There is a total compromise of system integrity. There is a complete loss of system protection, resulting in the entire system being compromised.)
Availability Impact Complete (There is a total shutdown of the affected resource. The attacker can render the resource completely unavailable.)
Access Complexity Medium (The access conditions are somewhat specialized. Some preconditions must be satistified to exploit)
Authentication ???
Gained Access None
Vulnerability Type(s) Denial Of Service
CWE ID 193

- Products Affected By CVE-2019-18423

# Product Type Vendor Product Version Update Edition Language
1 OS XEN XEN * * * * Version Details Vulnerabilities

- Number Of Affected Versions By Product

Vendor Product Vulnerable Versions
XEN XEN 1

- References For CVE-2019-18423

https://seclists.org/bugtraq/2020/Jan/21
BUGTRAQ 20200114 [SECURITY] [DSA 4602-1] xen security update
https://www.debian.org/security/2020/dsa-4602
DEBIAN DSA-4602
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/IZYATWNUGHRBG6I3TC24YHP5Y3J7I6KH/
FEDORA FEDORA-2019-cbb732f760
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/I5WWPW4BSZDDW7VHU427XTVXV7ROOFFW/
FEDORA FEDORA-2019-376ec5c107
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/2BQKX7M2RHCWDBKNPX4KEBI3MJIH6AYZ/
FEDORA FEDORA-2019-865bb16900
http://www.openwall.com/lists/oss-security/2019/10/31/4
MLIST [oss-security] 20191031 Xen Security Advisory 301 v3 (CVE-2019-18423) - add-to-physmap can be abused to DoS Arm hosts
http://xenbits.xen.org/xsa/advisory-301.html
https://security.gentoo.org/glsa/202003-56
GENTOO GLSA-202003-56

- Metasploit Modules Related To CVE-2019-18423

There are not any metasploit modules related to this CVE entry (Please visit www.metasploit.com for more information)


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