Spring Patches Two Flaws That Let Attackers Steal Secrets and Bypass WebSocket Security

 

CYBERDUDEBIVASH • ThreatWire

Published: October 17, 2025

Spring Patches Two Flaws That Let Attackers Steal Secrets and Bypass WebSocket Security

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Two Spring fixes close holes that could expose secrets and permit WebSocket auth bypass under specific configurations.

TL;DR: Recent Spring updates fix (1) a server-side info disclosure that can leak credentials/API keys through verbose error paths, and (2) a WebSocket handshake weakness that may allow cross-origin or unauthenticated socket upgrades in lax configurations. Patch all Spring runtimes now, restrict WebSocket origins, and tighten error/trace exposure in prod.

Audience: US • EU • UK • AU • IN Engineering leaders, Java platform owners, DevSecOps, SRE, SOC.

What’s impacted (at a glance)

• Spring MVC / WebFlux apps with custom exception handling or actuator endpoints exposed may leak secrets, tokens, or config values in certain error flows.
• Spring WebSocket / STOMP deployments that rely on permissive setAllowedOrigins("*"), missing origin checks, or weak handshake validation can be tricked into auth bypass / cross-site WebSocket hijacking.

Exploit sketch (defensive perspective)

1. Attacker sends a crafted HTTP request that triggers a deep error path or stack trace; verbose serialization/logback encoders echo sensitive values back to the client.
2. Separately, attacker initiates a WebSocket upgrade from a controlled origin; with wildcard CORS or mis-scoped interceptors, the upgrade succeeds without proper session/auth validation.

Immediate actions (patch-first)

1. Upgrade: Move to the latest Spring Framework and Spring Messaging/WebSocket point releases provided this week. Patch all services (prod/stage/dev).
2. Rebuild & redeploy containers/AMIs with fresh dependencies; do not hot-swap jars in place.
3. Rotate secrets (API keys, OAuth tokens, DB creds) if there’s any chance they were logged or surfaced via error responses.

WebSocket hardening 

// Only allow explicit origins (no "*")
@Override
public void registerStompEndpoints(StompEndpointRegistry registry) {
  registry.addEndpoint("/ws")
          .setAllowedOriginPatterns("https://app.example.com", "https://admin.example.com")
          .withSockJS(); // if you must; otherwise prefer native WS
}

// Enforce auth at handshake
@Component
public class AuthHandshakeInterceptor implements HandshakeInterceptor {
  @Override
  public boolean beforeHandshake(ServerHttpRequest req, ServerHttpResponse res,
                                 WebSocketHandler wsHandler, Map<String, Object> attrs) {
    // Validate session/JWT and Origin header
    // Reject if missing/invalid
    return isValid(req);
  }
  @Override public void afterHandshake(ServerHttpRequest r, ServerHttpResponse s,
                                       WebSocketHandler w, Exception e) {}
}

Stop secret leakage

• Disable stack traces and detailed error pages in prod (server.error.include-stacktrace=never).
• Sanitize exception mappers and @ControllerAdvice responses; never serialize config objects containing keys/tokens.
• Actuator: expose only over internal networks; require auth; remove env and configprops externally.
• Logging: adopt secret redaction in appenders/encoders and structured logging filters.

Detections for SOC/SIEM

• Surge in 101/400/500 series responses on endpoints that should be quiet, with unusually large payload sizes.
• WebSocket upgrades with unexpected Origin values or anonymous sessions; look for 101 Switching Protocols from non-trusted domains.
• Actuator probing: spikes on /actuator/env, /actuator/configprops, /error, /ws.

Blue-team checklist

1. Patch Spring Framework & Messaging/WebSocket to latest.
2. Lock down WebSocket origins; enforce handshake auth interceptors.
3. Turn off verbose error details; sanitize @ExceptionHandler outputs.
4. Gate actuator; limit to TLS + mTLS or VPN; remove public exposure.
5. Rotate secrets; enable vault-backed config (no plaintext in logs).
6. Add WAF rule to block cross-site WS upgrades and suspicious Sec-WebSocket-* headers.

Related on ThreatWire:

• Spring Framework security
• WebSocket / STOMP hardening
• WAF rules & API protection

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Educational, defensive use only. Test in staging before prod rollout; review origin lists and Actuator exposure policies.