CVE-2026-40564: Apache Flink Kubernetes Operator: Server-Side Request Forgery and local file access in Kubernetes Operator

[Gyula Fora <gyfora () apache org>]

Severity: moderate 

Affected versions:

- Apache Flink Kubernetes Operator 1.3.0 before 1.15.0

Description:

Files or Directories Accessible to External Parties, Server-Side Request Forgery (SSRF) vulnerability in Apache Flink 
Kubernetes Operator.

The FlinkSessionJob jarURI is currently not validated so that it points to user-owned files or addresses.  This lets a 
user with CR create permissions read files from the operator pod's filesystem and pull content from any backing store 
reachable through Flink's pluggable filesystem layer and access them through the submitted Flink job. Furthermore for 
fetching from http/https addresses there is currently no allowlist on the URI scheme, no host check, no IP-range 
restriction, and no protection against pointing the URI at internal or link-local addresses.This issue affects Apache 
Flink Kubernetes Operator: from 1.3.0 before 1.15.0.

Users are recommended to upgrade to version 1.15.0, which fixes the issue.

Credit:

Andrea Cosentino (finder)
Andrea Cosentino (remediation developer)

References:

https://flink.apache.org/
https://www.cve.org/CVERecord?id=CVE-2026-40564