CVE-2016-3091

Vulnerability

Diego-release versions 0.1468.0 through 0.1470.0 contain a flaw in how they handle breaking up large log streams on UTF-8 boundaries. When an app outputs malformed UTF-8 sequences, the component responsible for log splitting can be forced into a state that leads to a denial of service. This allows a remote attacker to disrupt the availability of a Cloud Foundry installation [1].

Exploitation

An attacker requires network access to deploy or interact with an application that can emit malformed UTF-8 sequences to the Diego log stream. The application's log output is processed by Diego's log subsystem, where the UTF-8 boundary splitting logic is triggered. By sending carefully crafted, malformed UTF-8 data repeatedly, the attacker can cause the log processing infrastructure to fail, resulting in a denial of service [1].

Impact

A successful exploit results in a denial of service (availability impact) to the Cloud Foundry deployment. The affected Diego components may become unresponsive or crash, preventing normal logging and potentially affecting application management and monitoring capabilities. No information disclosure or code execution is reported [1].

Mitigation

The Cloud Foundry project recommends upgrading to Diego version 0.1471.0, which contains the fix for this vulnerability. Deployments running any version between 0.1468.0 and 0.1470.0 should upgrade immediately to avoid the denial of service condition [1]. No workarounds are mentioned in the available reference.