CVE-2021-20219 Denial of service in kernel

What is CVE-2021-20219?

CVE-2021-20219 is a medium-severity denial of service vulnerability in Linux kernel, published on 23 Mar 2021. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

A denial of service vulnerability was found in n_tty_receive_char_special in drivers/tty/n_tty.c of the Linux kernel. In this flaw a local attacker with a normal user privilege could delay the loop (due to a changing ldata->read_head, and a missing sanity check) and cause a threat to the system availability.

Weakness: CWE-697

Which versions are affected by CVE-2021-20219?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2021-20219?

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-2021-20219 being exploited?

There is no known exploitation of CVE-2021-20219 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-4x74-wx76-5j5h, UBUNTU-CVE-2021-20219.