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Vulnerability Details : CVE-2020-11739

An issue was discovered in Xen through 4.13.x, allowing guest OS users to cause a denial of service or possibly gain privileges because of missing memory barriers in read-write unlock paths. The read-write unlock paths don't contain a memory barrier. On Arm, this means a processor is allowed to re-order the memory access with the preceding ones. In other words, the unlock may be seen by another processor before all the memory accesses within the "critical" section. As a consequence, it may be possible to have a writer executing a critical section at the same time as readers or another writer. In other words, many of the assumptions (e.g., a variable cannot be modified after a check) in the critical sections are not safe anymore. The read-write locks are used in hypercalls (such as grant-table ones), so a malicious guest could exploit the race. For instance, there is a small window where Xen can leak memory if XENMAPSPACE_grant_table is used concurrently. A malicious guest may be able to leak memory, or cause a hypervisor crash resulting in a Denial of Service (DoS). Information leak and privilege escalation cannot be excluded.
Publish Date : 2020-04-14 Last Update Date : 2021-07-21
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- CVSS Scores & Vulnerability Types

CVSS Score
6.9
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 Not required (Authentication is not required to exploit the vulnerability.)
Gained Access None
Vulnerability Type(s) Denial Of ServiceOverflowGain privilegesObtain Information
CWE ID 119

- Products Affected By CVE-2020-11739

# Product Type Vendor Product Version Update Edition Language
1 OS Fedoraproject Fedora 32 * * * Version Details Vulnerabilities
2 OS XEN XEN * * * * Version Details Vulnerabilities
3 OS XEN XEN 4.13.0 RC1 * * Version Details Vulnerabilities
4 OS XEN XEN 4.13.0 RC2 * * Version Details Vulnerabilities

- Number Of Affected Versions By Product

Vendor Product Vulnerable Versions
Fedoraproject Fedora 1
XEN XEN 3

- References For CVE-2020-11739

https://www.debian.org/security/2020/dsa-4723
DEBIAN DSA-4723
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/NVTP4OYHCTRU3ONFJOFJQVNDFB25KLLG/
FEDORA FEDORA-2020-cbc3149753
https://security.gentoo.org/glsa/202005-08
GENTOO GLSA-202005-08
http://lists.opensuse.org/opensuse-security-announce/2020-05/msg00006.html
SUSE openSUSE-SU-2020:0599
https://xenbits.xen.org/xsa/advisory-314.html
http://xenbits.xen.org/xsa/advisory-314.html CONFIRM
http://www.openwall.com/lists/oss-security/2020/04/14/2
MLIST [oss-security] 20200414 Xen Security Advisory 314 v3 (CVE-2020-11739) - Missing memory barriers in read-write unlock paths
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/5M2XRNCHOGGTJQBZQJ7DCV6ZNAKN3LE2/
FEDORA FEDORA-2020-295ed0b1e0
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/YMAW7D2MP6RE4BFI5BZWOBBWGY3VSOFN/
FEDORA FEDORA-2020-440457afe4

- Metasploit Modules Related To CVE-2020-11739

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


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