CVE-2020-29569 Use after free in n/a
A misbehaving guest can crash the host or potentially escalate privileges via a use-after-free in the Linux kernel PV block backend when rapidly toggling connections.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2020-29569?
CVE-2020-29569 is a high-severity use after free 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 the Linux kernel through 5.10.1, as used with Xen through 4.14.x. The Linux kernel PV block backend expects the kernel thread handler to reset ring->xenblkd to NULL when stopped. However, the handler may not have time to run if the frontend quickly toggles between the states connect and disconnect. As a consequence, the block backend may re-use a pointer after it was freed. A misbehaving guest can trigger a dom0 crash by continuously connecting / disconnecting a block frontend. Privilege escalation and information leaks cannot be ruled out. This only affects systems with a Linux blkback.
Weakness: CWE-416
Which versions are affected by CVE-2020-29569?
It affects 6 products.
Products include Debian Debian Linux, Linux kernel, Netapp Hci Compute Node Bios, Netapp Solidfire \& Hci Management Node, Netapp Solidfire \& Hci Storage Node, Xen Xen.
How do I fix CVE-2020-29569?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2020-29569 being exploited?
There is no known exploitation of CVE-2020-29569 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as ALPINE-CVE-2020-29569, DEBIAN-CVE-2020-29569, GHSA-6676-52pp-h5fg, UBUNTU-CVE-2020-29569.