CVE-2021-40391 Memory corruption in Gerbv

What is CVE-2021-40391?

CVE-2021-40391 is a critical memory corruption vulnerability in Debian Debian Linux, published on 19 Nov 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

An out-of-bounds write vulnerability exists in the drill format T-code tool number functionality of Gerbv 2.7.0, dev (commit b5f1eacd), and the forked version of Gerbv (commit 71493260). A specially-crafted drill file can lead to code execution. An attacker can provide a malicious file to trigger this vulnerability.

Weakness: CWE-787, CWE-755, CWE-390

Which versions are affected by CVE-2021-40391?

It affects 3 products.

Products include Debian Debian Linux, Fedoraproject Fedora, Gerbv Project Gerbv.

How do I fix CVE-2021-40391?

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-2021-40391 being exploited?

There is no known exploitation of CVE-2021-40391 in the wild and no public exploit code.

Other vulnerabilities in Debian Debian Linux

• CVE-2015-3306 ProFTPD Improper Access Control Exploited Critical 10.0
• CVE-2025-49113 RoundCube Webmail Deserialization of Untrusted Data Exploited Critical 9.9
• CVE-2026-24061 GNU InetUtils Argument Injection Exploited Critical 9.8
• CVE-2025-39682 Linux Kernel Improper Check for Unusual or Exceptional Conditions Exploited Critical 9.8
• CVE-2024-9680 Mozilla Firefox Use-After-Free Exploited Critical 9.8

All Debian Debian Linux vulnerabilities

Sources

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

Also known as DEBIAN-CVE-2021-40391, DLA-2839-1, GHSA-3x4w-8mh5-3xjq, UBUNTU-CVE-2021-40391.