Information disclosure in tectonic - CVE-2018-5256

Detailed vulnerability description

The vulnerability allows a remote non-authenticated attacker to gain access to sensitive information.

CoreOS Tectonic 1.7.x before 1.7.9-tectonic.4 and 1.8.x before 1.8.4-tectonic.3 mounts a direct proxy to the kubernetes cluster at /api/kubernetes/ which is accessible without authentication to Tectonic and allows an attacker to directly connect to the kubernetes API server. Unauthenticated users are able to list all Namespaces through the Console, resulting in an information disclosure. Tectonic's exposure of an unauthenticated API endpoint containing information regarding the internal state of the cluster can provide an attacker with information that may assist in other attacks against the cluster. For example, an attacker may not have the permissions required to list all namespaces in the cluster but can instead leverage this vulnerability to enumerate the namespaces and then begin to check each namespace for weak authorization policies that may allow further escalation of privileges.

How to mitigate CVE-2018-5256

Sources

• https://coreos.com/blog/tectonic-namespace-information-disclosure-vulnerability-patched
• https://coreos.com/tectonic/releases/#1.8.4-tectonic.3