CVE-2021-3973 Heap-based Buffer Overflow in vim/vim

High 7.3 Published 19 Nov 2021 Updated 8 Oct 2026

A heap-based buffer overflow in Vim allows attackers to execute arbitrary code or cause a denial of service via crafted input.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Local or same network only
Victim action needed: A user has to click or open something
Fix: Available

What is CVE-2021-3973?

CVE-2021-3973 is a high-severity memory corruption vulnerability in Debian Debian Linux, published on 19 Nov 2021. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

Official description

vim is vulnerable to Heap-based Buffer Overflow

Weakness: CWE-787, CWE-122

Which versions are affected by CVE-2021-3973?

It affects 3 products.

Products include Debian Debian Linux, Fedoraproject Fedora, Vim Vim.

How do I fix CVE-2021-3973?

Apply the vendor's patch.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2021-3973 being exploited?

There is no known exploitation of CVE-2021-3973 in the wild and no public exploit code.

All Debian Debian Linux vulnerabilities

Sources

Also known as ALPINE-CVE-2021-3973, AZL-6946, DEBIAN-CVE-2021-3973, GHSA-ppq4-g8vp-2cv6, UBUNTU-CVE-2021-3973.