4.9 Medium
CVSS2
Attack Vector
LOCAL
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
COMPLETE
AV:L/AC:L/Au:N/C:N/I:N/A:C
6 Medium
CVSS3
Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
HIGH
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H
0.0004 Low
EPSS
Percentile
5.1%
When a Xenstore watch fires, the xenstore client which registered the watch will receive a Xenstore message containing the path of the modified Xenstore entry which triggered the watch, and the tag which was specified when registering the watch.
Any communication with xenstored is done via Xenstore messages, consisting of a message header and the payload. The payload length is limited to 4096 bytes. Any request to xenstored resulting in a response with a payload longer than 4096 bytes will result in an error.
When registering a watch the payload length limit applies to the combined length of the watched path and the specified tag. As watches for a specific path are also triggered for all nodes below that path, the payload of a watch event message can be longer than the payload needed to register the watch.
A malicious guest which registers a watch using a very large tag (ie with a registration operation payload length close to the 4096 byte limit) can cause the generation of watch events with a payload length larger than 4096 bytes, by writing to Xenstore entries below the watched path.
This will result in an error condition in xenstored. This error can result in a NULL pointer dereference leading to a crash of xenstored.
A malicious guest administrator can cause xenstored to crash, leading to a denial of service. Following a xenstored crash, domains may continue to run, but management operations will be impossible.
All Xen versions are affected.
Only C xenstored is affected, oxenstored is not affected.
4.9 Medium
CVSS2
Attack Vector
LOCAL
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
COMPLETE
AV:L/AC:L/Au:N/C:N/I:N/A:C
6 Medium
CVSS3
Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
HIGH
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H
0.0004 Low
EPSS
Percentile
5.1%