CVE-2020-15566

MEDIUM
New! CVE Severity Now Using CVSS v3

The calculated severity for CVEs has been updated to use CVSS v3 by default. CVEs that do not have a CVSS v3 score will fall back CVSS v2 for calculating severity. Severity display preferences can be toggled in the settings dropdown.

Description

An issue was discovered in Xen through 4.13.x, allowing guest OS users to cause a host OS crash because of incorrect error handling in event-channel port allocation. The allocation of an event-channel port may fail for multiple reasons: (1) port is already in use, (2) the memory allocation failed, or (3) the port we try to allocate is higher than what is supported by the ABI (e.g., 2L or FIFO) used by the guest or the limit set by an administrator (max_event_channels in xl cfg). Due to the missing error checks, only (1) will be considered an error. All the other cases will provide a valid port and will result in a crash when trying to access the event channel. When the administrator configured a guest to allow more than 1023 event channels, that guest may be able to crash the host. When Xen is out-of-memory, allocation of new event channels will result in crashing the host rather than reporting an error. Xen versions 4.10 and later are affected. All architectures are affected. The default configuration, when guests are created with xl/libxl, is not vulnerable, because of the default event-channel limit.

References

http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00024.html

http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00031.html

http://www.openwall.com/lists/oss-security/2020/07/07/2

http://xenbits.xen.org/xsa/advisory-317.html

https://lists.fedoraproject.org/archives/list/[email protected]/message/MXESCOVI7AVRNC7HEAMFM7PMEO6D3AUH/

https://lists.fedoraproject.org/archives/list/[email protected]/message/VB3QJJZV23Z2IDYEMIHELWYSQBUEW6JP/

https://security.gentoo.org/glsa/202007-02

https://www.debian.org/security/2020/dsa-4723

Details

Source: MITRE

Published: 2020-07-07

Updated: 2020-07-27

Type: CWE-755

Risk Information

CVSS v2

Base Score: 4.7

Vector: AV:L/AC:M/Au:N/C:N/I:N/A:C

Impact Score: 6.9

Exploitability Score: 3.4

Severity: MEDIUM

CVSS v3

Base Score: 6.5

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H

Impact Score: 4

Exploitability Score: 2

Severity: MEDIUM

Vulnerable Software

Configuration 1

OR

cpe:2.3:o:xen:xen:*:*:*:*:*:*:*:* versions from 4.10.0 to 4.13.1 (inclusive)

Configuration 2

OR

cpe:2.3:o:debian:debian_linux:10:*:*:*:*:*:*:*

Tenable Plugins

View all (10 total)

IDNameProductFamilySeverity
138925GLSA-202007-02 : Xen: Multiple vulnerabilitiesNessusGentoo Local Security Checks
high
138864Fedora 31 : xen (2020-76cf2b0f0a)NessusFedora Local Security Checks
high
138749openSUSE Security Update : xen (openSUSE-2020-985)NessusSuSE Local Security Checks
high
138741openSUSE Security Update : xen (openSUSE-2020-965)NessusSuSE Local Security Checks
high
138535Fedora 32 : xen (2020-fbc13516af)NessusFedora Local Security Checks
high
138495SUSE SLED15 / SLES15 Security Update : xen (SUSE-SU-2020:1902-1)NessusSuSE Local Security Checks
high
138492SUSE SLES12 Security Update : xen (SUSE-SU-2020:1891-1)NessusSuSE Local Security Checks
high
138434SUSE SLED15 / SLES15 Security Update : xen (SUSE-SU-2020:1889-1)NessusSuSE Local Security Checks
high
138433SUSE SLES12 Security Update : xen (SUSE-SU-2020:1887-1)NessusSuSE Local Security Checks
high
138394Debian DSA-4723-1 : xen - security updateNessusDebian Local Security Checks
high