CVE-2020-29484 Null dereference in n/a
A malicious guest administrator can crash the C xenstored service via a NULL pointer dereference, causing a denial of service for management operations.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2020-29484?
CVE-2020-29484 is a medium-severity vulnerability in Debian Debian Linux, published on 15 Dec 2020. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
An issue was discovered in Xen through 4.14.x. When a Xenstore watch fires, the xenstore client that registered the watch will receive a Xenstore message containing the path of the modified Xenstore entry that triggered the watch, and the tag that 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. Because 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 that registers a watch using a very large tag (i.e., 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. Only C xenstored is affected, oxenstored is not affected.
Weakness: CWE-476
Which versions are affected by CVE-2020-29484?
It affects 3 products.
Products include Debian Debian Linux, Fedoraproject Fedora, Xen Xen.
How do I fix CVE-2020-29484?
Apply the vendor's patch.
Is CVE-2020-29484 being exploited?
There is no known exploitation of CVE-2020-29484 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as ALPINE-CVE-2020-29484, DEBIAN-CVE-2020-29484, GHSA-58pp-88x2-wf7f, UBUNTU-CVE-2020-29484.