CVE-2021-4159 Information disclosure in kernel

What is CVE-2021-4159?

CVE-2021-4159 is a medium-severity vulnerability in Debian Debian Linux, published on 24 Aug 2022. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

A vulnerability was found in the Linux kernel's EBPF verifier when handling internal data structures. Internal memory locations could be returned to userspace. A local attacker with the permissions to insert eBPF code to the kernel can use this to leak internal kernel memory details defeating some of the exploit mitigations in place for the kernel.

Weakness: CWE-202

Which versions are affected by CVE-2021-4159?

It affects 3 products.

Products include Debian Debian Linux, Linux kernel, Redhat Enterprise Linux.

How do I fix CVE-2021-4159?

Apply the vendor's patch.

Is CVE-2021-4159 being exploited?

There is no known exploitation of CVE-2021-4159 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-2021-4159, GHSA-4f4x-m5ww-4mcw, UBUNTU-CVE-2021-4159.