CVE-2023-23939: Azure/setup-kubectl: Escalation of privilege vulnerability for v3 and lower

Vulnerability summary

CVE-2023-23939 is a high (CVSS 7.0) vulnerability in azure setup-kubectl. EPSS estimates a 0.36% chance of exploitation in the next 30 days, higher than 28.7% of scored vulnerabilities.

Timeline

1. 06-03-2023
   PublishedVulnerability first disclosed.
2. 25-02-2025
   Last modifiedVulnerability information updated.

Description

Azure/setup-kubectl is a GitHub Action for installing Kubectl. This vulnerability only impacts versions before version 3. An insecure temporary creation of a file allows other actors on the Actions runner to replace the Kubectl binary created by this action because it is world writable. This Kubectl tool installer runs `fs.chmodSync(kubectlPath, 777)` to set permissions on the Kubectl binary, however, this allows any local user to replace the Kubectl binary. This allows privilege escalation to the user that can also run kubectl, most likely root. This attack is only possible if an attacker somehow breached the GitHub actions runner or if a user is utilizing an Action that maliciously executes this attack. This has been fixed and released in all versions `v3` and later. 775 permissions are used instead. Users are advised to upgrade. There are no known workarounds for this issue.

• CWE-732Incorrect Permission Assignment for Critical ResourceThe product specifies permissions for a security-critical resource in a way that allows that resource to be read or modified by unintended actors.