CVE-2021-31999 Rancher: Privilege escalation vulnerability via malicious Connection header

What is CVE-2021-31999?

CVE-2021-31999 is a high-severity vulnerability in Rancher, published on 15 Jul 2021. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

A Reliance on Untrusted Inputs in a Security Decision vulnerability in Rancher allows users in the cluster to act as others users in the cluster by forging the "Impersonate-User" or "Impersonate-Group" headers. This issue affects: Rancher versions prior to 2.5.9. Rancher versions prior to 2.4.16.

Weakness: CWE-807

Which versions are affected by CVE-2021-31999?

5 open source packages ship an affected version, including github.com/rancher/rancher. It affects 1 product.

Products include Rancher Rancher.

How do I fix CVE-2021-31999?

Upgrade github.com/rancher/rancher to a fixed version for your release line: 2.4.16 or 2.5.9.

Is CVE-2021-31999 being exploited?

There is no known exploitation of CVE-2021-31999 in the wild and no public exploit code.

Other vulnerabilities in Rancher

• CVE-2021-25320 Rancher: Cloud credentials can be used through proxy API by users without access Critical 9.9
• CVE-2021-36775 Deleting PRTBs associated to a group doesn't cause deletion of corresponding RoleBindings High 8.8
• CVE-2021-36776 Steve API proxy impersonation High 8.8
• CVE-2021-25318 rancher: API group not properly specified when creating Kubernetes RBAC resources High 8.8

Sources

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

Also known as GHSA-pvxj-25m6-7vqr, GO-2024-2778.