Medium [CVE-2026-40557] Apache Storm Prometheus: Improper Certificate Validation
This medium-severity Apache Software Foundation advisory covers CVE-2026-40557 affecting Apache Storm Prometheus, ZooKeeper.
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Summary
Improper Certificate Validation via Global SSL Context Downgrade in Apache Storm Prometheus Reporter
Versions Affected: from 2.6.3 to 2.8.6
In production deployments where an administrator enables storm.daemon.metrics.reporter.plugin.prometheus.skip_tls_validation (by default it is disabled) intending to affect only the Prometheus reporter, the undocumented global side effect creates an attack surface across every TLS-protected communication channel in the Storm daemon.
The PrometheusPreparableReporter class implements an INSECURE_TRUST_MANAGER that accepts all SSL certificates without validation, with empty checkClientTrusted and checkServerTrusted methods.
Most critically, when the storm.daemon.metrics.reporter.plugin.prometheus.skip_tls_validation configuration option is enabled (default = disabled) for HTTPS Prometheus PushGateway connections, the INSECURE_CONNECTION_FACTORY calls SSLContext.setDefault(sslContext), which globally replaces the JVM's default SSL context rather than applying the insecure context only to the Prometheus connection.
This payload flows through storm.yaml configuration → PrometheusPreparableReporter.prepare() → INSECURE_CONNECTION_FACTORY → SSLContext.setDefault(), resulting in a JVM-wide TLS security downgrade.
- 2.6.3 through 2.8.6
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
Mitigation
Upgrade to a fixed release: 2.8.7. That is the remediation for this advisory.
The vendor advisory may list additional interim mitigations or workarounds not captured here — review it before change work.
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
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