CVE-2021-20219

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-03-23 · updated 2026-06-17
Weakness: CWE-697

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.

Affected products

Linux kernel: before 4.18 — fixed in 4.18

How to fix

Upgrade to a fixed version: Linux kernel 4.18. Check the vendor advisory for mitigations.

References

https://bugzilla.redhat.com/show_bug.cgi?id=1923738
https://bugzilla.redhat.com/show_bug.cgi?id=1923738

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