CVE-2021-20177 Denial of service in kernel
A privileged user can cause a system panic by inserting specific iptables rules due to a flaw in kernel packet string matching.
- 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-2021-20177?
CVE-2021-20177 is a medium-severity denial of service vulnerability in Linux kernel, published on 26 May 2021. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
A flaw was found in the Linux kernel's implementation of string matching within a packet. A privileged user (with root or CAP_NET_ADMIN) when inserting iptables rules could insert a rule which can panic the system. Kernel before kernel 5.5-rc1 is affected.
Weakness: CWE-125
Which versions are affected by CVE-2021-20177?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2021-20177?
Upgrade to a fixed version.
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-2021-20177 being exploited?
There is no known exploitation of CVE-2021-20177 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2021-20177, GHSA-8hpj-w92q-gf6m, UBUNTU-CVE-2021-20177.