CVE-2021-20257 Denial of service in QEMU
A guest can trigger an infinite loop in the QEMU e1000 NIC emulator, consuming host CPU cycles and causing a denial of service.
- 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-2021-20257?
CVE-2021-20257 is a medium-severity denial of service vulnerability in Debian Debian Linux, published on 16 Mar 2022. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
An infinite loop flaw was found in the e1000 NIC emulator of the QEMU. This issue occurs while processing transmits (tx) descriptors in process_tx_desc if various descriptor fields are initialized with invalid values. This flaw allows a guest to consume CPU cycles on the host, resulting in a denial of service. The highest threat from this vulnerability is to system availability.
Weakness: CWE-835
Which versions are affected by CVE-2021-20257?
It affects 8 products.
Products include Debian Debian Linux, Fedoraproject Fedora, Qemu Qemu, Redhat Codeready Linux Builder, Redhat Enterprise Linux, Redhat Enterprise Linux for Ibm Z Systems and 2 more.
How do I fix CVE-2021-20257?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2021-20257 being exploited?
There is no known exploitation of CVE-2021-20257 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as AZL-9068, DEBIAN-CVE-2021-20257, GHSA-j586-x8f6-9xf2, UBUNTU-CVE-2021-20257.