Xen up to 4.14.x Event Channel denial of service

Summaryinfo

A vulnerability marked as critical has been reported in Xen up to 4.14.x. Affected is an unknown function of the component Event Channel Handler. This manipulation causes denial of service. The identification of this vulnerability is CVE-2020-25600. There is no exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Xen up to 4.14.x (Virtualization Software). It has been declared as critical. Affected by this vulnerability is an unknown code of the component Event Channel Handler. The manipulation with an unknown input leads to a denial of service vulnerability. The CWE definition for the vulnerability is CWE-404. The product does not release or incorrectly releases a resource before it is made available for re-use. As an impact it is known to affect availability. The summary by CVE is:

An issue was discovered in Xen through 4.14.x. Out of bounds event channels are available to 32-bit x86 domains. The so called 2-level event channel model imposes different limits on the number of usable event channels for 32-bit x86 domains vs 64-bit or Arm (either bitness) ones. 32-bit x86 domains can use only 1023 channels, due to limited space in their shared (between guest and Xen) information structure, whereas all other domains can use up to 4095 in this model. The recording of the respective limit during domain initialization, however, has occurred at a time where domains are still deemed to be 64-bit ones, prior to actually honoring respective domain properties. At the point domains get recognized as 32-bit ones, the limit didn't get updated accordingly. Due to this misbehavior in Xen, 32-bit domains (including Domain 0) servicing other domains may observe event channel allocations to succeed when they should really fail. Subsequent use of such event channels would then possibly lead to corruption of other parts of the shared info structure. An unprivileged guest may cause another domain, in particular Domain 0, to misbehave. This may lead to a Denial of Service (DoS) for the entire system. All Xen versions from 4.4 onwards are vulnerable. Xen versions 4.3 and earlier are not vulnerable. Only x86 32-bit domains servicing other domains are vulnerable. Arm systems, as well as x86 64-bit domains, are not vulnerable.

The weakness was shared 09/23/2020. This vulnerability is known as CVE-2020-25600 since 09/16/2020. Neither technical details nor an exploit are publicly available.

Upgrading eliminates this vulnerability.

The entries VDB-161813, VDB-161812, VDB-161811 and VDB-161810 are related to this item. Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Affected

• Xen
• Citrix Hypervisor up to 8.2 LTSR

Productinfo

Type

• Virtualization Software

Name

• Xen

Version

• 4.0
• 4.1
• 4.2
• 4.3
• 4.4
• 4.5
• 4.6
• 4.7
• 4.8
• 4.9
• 4.10
• 4.11
• 4.12
• 4.13
• 4.14

License

• open-source

CPE 2.3info

• 🔍
• 🔍
• 🔍

CPE 2.2info

• 🔍
• 🔍
• 🔍

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CVSSv3info

CVSSv2info

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Threat Intelligenceinfo

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Sourcesinfo

Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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