CVE-2026-40557

import javax.net.ssl.*; import java.io.IOException; import java.net.URL; import java.security.KeyManagementException; import java.security.NoSuchAlgorithmException; import java.security.cert.X509Certificate; // PoC simulating the vulnerable behavior in Apache Storm PrometheusPreparableReporter public class VulnerableSSLContext { public static void main(String[] args) throws NoSuchAlgorithmException, KeyManagementException, IOException { System.out.println("[+] Simulating CVE-2026-40557: Global SSL Context Downgrade"); // 1. Create an insecure TrustManager (matches INSECURE_TRUST_MANAGER) TrustManager[] trustAllCerts = new TrustManager[] { new X509TrustManager() { public X509Certificate[] getAcceptedIssuers() { return null; } public void checkClientTrusted(X509Certificate[] certs, String authType) { /* Empty/Vulnerable */ } public void checkServerTrusted(X509Certificate[] certs, String authType) { /* Empty/Vulnerable */ } } }; // 2. Initialize SSLContext SSLContext sslContext = SSLContext.getInstance("TLS"); sslContext.init(null, trustAllCerts, new java.security.SecureRandom()); // 3. VULNERABLE OPERATION: Setting the global default SSLContext // This is what PrometheusPreparableReporter does when skip_tls_validation is true SSLContext.setDefault(sslContext); System.out.println("[!] Global SSLContext has been set to INSECURE mode."); // 4. Proof of Concept: Opening a connection to any HTTPS site will now ignore certificate validation // (Simulating subsequent connections to ZooKeeper, Thrift, etc.) URL url = new URL("https://expired.badssl.com/"); // A site with invalid cert HttpsURLConnection conn = (HttpsURLConnection) url.openConnection(); conn.setRequestMethod("GET"); try { conn.connect(); System.out.println("[+] Connection successful! Certificate validation was bypassed globally."); System.out.println("[+] Response Code: " + conn.getResponseCode()); } catch (Exception e) { System.out.println("[-] Connection failed (should not happen if vulnerable)."); } } }

{"cve": {"id": "CVE-2026-40557", "sourceIdentifier": "[email protected]", "published": "2026-04-27T14:16:48.017", "lastModified": "2026-05-05T18:11:10.203", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Improper Certificate Validation via Global SSL Context Downgrade in Apache Storm Prometheus Reporter\n\n\nVersions Affected: from 2.6.3 to 2.8.6\n\n\nDescription: \n\nIn 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.\n\n\nThe 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.\n\n\n\n\nMitigation: 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."}], "metrics": {"cvssMetricV31": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N", "baseScore": 4.8, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.2, "impactScore": 2.5}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-295"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:apache:storm_prometheus_reporter:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.3", "versionEndExcluding": "2.8.7", "matchCriteriaId": "3BAEE5C8-86FE-4927-BB10-A14FFF4BFD75"}]}]}], "references": [{"url": "https://lists.apache.org/thread/f5bv68z1y5xstz22psjk05p3wn86knjq", "source": "[email protected]", "tags": ["Mailing List", "Vendor Advisory"]}, {"url": "http://www.openwall.com/lists/oss-security/2026/04/25/2", "source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Mailing List", "Third Party Advisory"]}]}}