CVE-2021-21334 environment variable leak

What is CVE-2021-21334?

CVE-2021-21334 is a medium-severity vulnerability in Fedoraproject Fedora, published on 10 Mar 2021. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

In containerd (an industry-standard container runtime) before versions 1.3.10 and 1.4.4, containers launched through containerd's CRI implementation (through Kubernetes, crictl, or any other pod/container client that uses the containerd CRI service) that share the same image may receive incorrect environment variables, including values that are defined for other containers. If the affected containers have different security contexts, this may allow sensitive information to be unintentionally shared. If you are not using containerd's CRI implementation (through one of the mechanisms described above), you are not vulnerable to this issue. If you are not launching multiple containers or Kubernetes pods from the same image which have different environment variables, you are not vulnerable to this issue. If you are not launching multiple containers or Kubernetes pods from the same image in rapid succession, you have reduced likelihood of being vulnerable to this issue This vulnerability has been fixed in containerd 1.3.10 and containerd 1.4.4. Users should update to these versions.

Weakness: CWE-668

Which versions are affected by CVE-2021-21334?

4 open source packages ship an affected version, including github.com/containerd/containerd. It affects 2 products.

Products include Fedoraproject Fedora, Linuxfoundation Containerd.

How do I fix CVE-2021-21334?

Upgrade github.com/containerd/containerd to a fixed version for your release line: 1.3.10 or 1.4.4.

Is CVE-2021-21334 being exploited?

There is no known exploitation of CVE-2021-21334 in the wild and no public exploit code.

Other vulnerabilities in Fedoraproject Fedora

• CVE-2024-4577 PHP-CGI OS Command Injection Exploited Critical 9.8
• CVE-2021-39226 Grafana Authentication Bypass Exploited Critical 9.8
• CVE-2019-5544 VMware ESXi and Horizon DaaS OpenSLP Heap-Based Buffer Overflow Exploited Critical 9.8
• CVE-2024-4947 Google Chromium V8 Type Confusion Exploited Critical 9.6
• CVE-2024-4671 Google Chromium Visuals Use-After-Free Exploited Critical 9.6

All Fedoraproject Fedora vulnerabilities

Sources

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

Also known as AZL-44910, AZL-81209, CLEANSTART-2025-BS91981, DEBIAN-CVE-2021-21334, GHSA-6g2q-w5j3-fwh4, MGASA-2021-0248 and 2 more.