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Vulnerability Details : CVE-2020-15565

An issue was discovered in Xen through 4.13.x, allowing x86 Intel HVM guest OS users to cause a host OS denial of service or possibly gain privileges because of insufficient cache write-back under VT-d. When page tables are shared between IOMMU and CPU, changes to them require flushing of both TLBs. Furthermore, IOMMUs may be non-coherent, and hence prior to flushing IOMMU TLBs, a CPU cache also needs writing back to memory after changes were made. Such writing back of cached data was missing in particular when splitting large page mappings into smaller granularity ones. A malicious guest may be able to retain read/write DMA access to frames returned to Xen's free pool, and later reused for another purpose. Host crashes (leading to a Denial of Service) and privilege escalation cannot be ruled out. Xen versions from at least 3.2 onwards are affected. Only x86 Intel systems are affected. x86 AMD as well as Arm systems are not affected. Only x86 HVM guests using hardware assisted paging (HAP), having a passed through PCI device assigned, and having page table sharing enabled can leverage the vulnerability. Note that page table sharing will be enabled (by default) only if Xen considers IOMMU and CPU large page size support compatible.
Publish Date : 2020-07-07 Last Update Date : 2020-07-27
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- CVSS Scores & Vulnerability Types

CVSS Score
6.1
Confidentiality Impact Partial (There is considerable informational disclosure.)
Integrity Impact Partial (Modification of some system files or information is possible, but the attacker does not have control over what can be modified, or the scope of what the attacker can affect is limited.)
Availability Impact Complete (There is a total shutdown of the affected resource. The attacker can render the resource completely unavailable.)
Access Complexity Low (Specialized access conditions or extenuating circumstances do not exist. Very little knowledge or skill is required to exploit. )
Authentication Not required (Authentication is not required to exploit the vulnerability.)
Gained Access None
Vulnerability Type(s) Denial Of ServiceGain privileges
CWE ID 400

- Products Affected By CVE-2020-15565

# Product Type Vendor Product Version Update Edition Language
1 OS Debian Debian Linux 10.0 * * * Version Details Vulnerabilities
2 OS XEN XEN * * * * Version Details Vulnerabilities

- Number Of Affected Versions By Product

Vendor Product Vulnerable Versions
Debian Debian Linux 1
XEN XEN 1

- References For CVE-2020-15565

http://xenbits.xen.org/xsa/advisory-321.html
http://www.openwall.com/lists/oss-security/2020/07/07/4
MLIST [oss-security] 20200707 Xen Security Advisory 321 v3 (CVE-2020-15565) - insufficient cache write-back under VT-d
https://www.debian.org/security/2020/dsa-4723
DEBIAN DSA-4723
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00024.html
SUSE openSUSE-SU-2020:0965
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/VB3QJJZV23Z2IDYEMIHELWYSQBUEW6JP/
FEDORA FEDORA-2020-fbc13516af
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00031.html
SUSE openSUSE-SU-2020:0985
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/MXESCOVI7AVRNC7HEAMFM7PMEO6D3AUH/
FEDORA FEDORA-2020-76cf2b0f0a
https://security.gentoo.org/glsa/202007-02
GENTOO GLSA-202007-02

- Metasploit Modules Related To CVE-2020-15565

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


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