CVE-2020-17518 : Security Advisory and Response

Apache Flink 1.5.1 to 1.11.2 allows remote file writing through a directory traversal attack via the REST API.

Understanding CVE-2020-17518

Apache Flink vulnerability enabling malicious file writing through the REST API.

What is CVE-2020-17518?

Apache Flink 1.5.1 introduced a REST handler allowing file writing to any accessible location.

The Impact of CVE-2020-17518

Attackers can write files to arbitrary locations on the local file system.

Technical Details of CVE-2020-17518

Apache Flink vulnerability details and affected systems.

Vulnerability Description

Introduced in Apache Flink 1.5.1, the REST handler permits file writing through HTTP HEADER manipulation.

Affected Systems and Versions

Product: Apache Flink
Vendor: Apache Software Foundation
Versions: 1.5.1 to 1.11.2

Exploitation Mechanism

Malicious HTTP HEADER modification allows writing files to any accessible location.

Mitigation and Prevention

Protective measures and steps to address CVE-2020-17518.

Immediate Steps to Take

Upgrade to Flink 1.11.3 or 1.12.0 if using affected versions.

Long-Term Security Practices

Implement strict input validation to prevent directory traversal attacks.
Regularly monitor and update security patches.
Follow secure coding practices to mitigate similar vulnerabilities.

Patching and Updates

Apply the fix in commit a5264a6f41524afe8ceadf1d8ddc8c80f323ebc4 from apache/flink:master.