CVE-2021-3653 Privilege escalation in kernel

What is CVE-2021-3653?

CVE-2021-3653 is a high-severity vulnerability in Debian Debian Linux, published on 29 Sep 2021. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

A flaw was found in the KVM's AMD code for supporting SVM nested virtualization. The flaw occurs when processing the VMCB (virtual machine control block) provided by the L1 guest to spawn/handle a nested guest (L2). Due to improper validation of the "int_ctl" field, this issue could allow a malicious L1 to enable AVIC support (Advanced Virtual Interrupt Controller) for the L2 guest. As a result, the L2 guest would be allowed to read/write physical pages of the host, resulting in a crash of the entire system, leak of sensitive data or potential guest-to-host escape. This flaw affects Linux kernel versions prior to 5.14-rc7.

Weakness: CWE-862

Which versions are affected by CVE-2021-3653?

It affects 3 products.

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

How do I fix CVE-2021-3653?

Apply the vendor's patch.

Is CVE-2021-3653 being exploited?

There is no known exploitation of CVE-2021-3653 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 ALSA-2021:3548, AZL-6575, DEBIAN-CVE-2021-3653, GHSA-g58x-c6rr-7fp2, RHSA-2021:3547, RHSA-2021:3548 and 4 more.