CVE-2021-3968 Heap-based Buffer Overflow in vim/vim

High 8.0 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: Any signed-in user
Attackable: Over the internet
Victim action needed: A user has to click or open something
Fix: Available

What is CVE-2021-3968?

CVE-2021-3968 is a high-severity memory corruption vulnerability in Fedoraproject Fedora, published on 19 Nov 2021. Any signed-in user can exploit it over the 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-2021-3968?

It affects 2 products.

Products include Fedoraproject Fedora, Vim Vim.

How do I fix CVE-2021-3968?

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-2021-3968 being exploited?

There is no known exploitation of CVE-2021-3968 in the wild and no public exploit code.

All Fedoraproject Fedora vulnerabilities

Sources

Also known as ALPINE-CVE-2021-3968, AZL-6945, DEBIAN-CVE-2021-3968, GHSA-p5c5-45cp-hjw4.