CVE-2026-40557

Improper Certificate Validation via Global SSL Context Downgrade in Apache Storm Prometheus Reporter Versions Affected: from 2.6.3 to 2.8.6 Description:  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. All subsequent HTTPS connections in the process - including ZooKeeper, Thrift, Netty, and UI connections - silently trust all certificates, including self-signed, expired, and attacker-generated ones, enabling man-in-the-middle interception of cluster state, topology submissions, tuple data, and administrative credentials. Mitigation: 2.x users should upgrade to 2.8.7 if the Prometheus Metrics Reporter is used. Prometheus Metrics Reporter Users who cannot upgrade immediately should remove the storm.daemon.metrics.reporter.plugin.prometheus.skip_tls_validation: true setting from their storm.yaml configuration and instead configure a proper truststore containing the PushGateway's certificate.

CVSS 3.1

4.8CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

EPSS

0.2% chance of exploitation in the next 30 days; higher than 8% of CVEs (scores of 2026-10-26)

CWE

CWE-295

Published

2026-04-27

Modified

2026-10-26

Record from

the NVD, synced 2026-10-26

Affected

• apache:storm_prometheus_reporter

Packages (OSV)

References

• https://lists.apache.org/thread/f5bv68z1y5xstz22psjk05p3wn86knjq
• http://www.openwall.com/lists/oss-security/2026/04/25/2

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