CVE-2025-41254: Spring WebSocket CSRF Bypass Vulnerability Explained

A new vulnerability (CVE-2025-41254) has been identified in the Spring Framework’s spring-websocket module. This issue allows attackers to send unauthorized messages in STOMP over WebSocket applications — bypassing the expected session creation phase entirely.

This vulnerability carries a medium severity rating and affects multiple Spring Framework versions, including:

• 6.2.0 to 6.2.11
• 6.1.0 to 6.1.23
• 6.0.0 to 6.0.29
• 5.3.0 to 5.3.45
• 4.3.0 to 4.3.30
• Other versions prior to 5.3.0

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What’s the Risk

Normally, WebSocket servers enforce a connection handshake process before allowing clients to SUBSCRIBE or SEND messages.

In vulnerable versions of Spring WebSocket, an attacker can bypass this validation. Attackers can then deliver payloads to WebSocket controllers allowing them to execute application logic not intended for unauthenticated users.

Depending on the application’s implementation, this flaw can lead to:

• Cross-Site Request Forgery (CSRF) attacks through unauthorized message delivery‍
• Privilege escalation or business logic manipulation‍
• Unauthorized data access via crafted STOMP payloads
  

While the vulnerability doesn’t directly compromise authentication or encryption, it exposes an unexpected message path that can be exploited under the right conditions.

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Why It Matters

Spring WebSocket is widely used in enterprise Java applications — powering chat systems, live updates, event-driven architectures, and microservice communication.

A CSRF-style exploit in these systems can:

• Compromise data integrity by spoofing valid message traffic
• Disrupt session logic or authorization layers
• Create unpredictable downstream security implications
  
  

Even a medium-severity issue like this can pose real-world risk in high-traffic or customer-facing systems.

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The HeroDevs Fix

HeroDevs has already patched this issue in our Never-Ending Support (NES) builds for Spring Framework. The vulnerability is resolved in:

• Spring Framework 4.3.46 (NES)
  
  
• Spring Framework 5.3.49 (NES)
  
  
• Spring Framework 6.1.25 (NES)
  
  

These patched builds ensure WebSocket connections follow proper session validation and prevent any unauthorized message delivery attempts.

If you’re currently running an affected version of Spring Framework — including EOL versions that no longer receive official support — you can apply the HeroDevs NES patch to stay secure while maintaining production stability.

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What You Should Do

1. Identify Vulnerable Versions
Check your application’s dependency tree for spring-websocket. If you’re running one of the affected versions listed above, assume exposure.

2. Upgrade or Patch

• Upgrade to a supported Spring Framework version that includes the fix.
• Or apply HeroDevs’ NES for Spring Framework patch to receive the remediation immediately.
  
  

3. Validate Your WebSocket Behavior
Ensure that your application’s message-handling logic requires proper websocket session creation before sending additional messages.

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Final Take

This vulnerability is a reminder that even subtle protocol inconsistencies can expose enterprise systems to significant risk.

With HeroDevs NES for Spring, you can continue running stable, legacy Spring versions securely — without rushed migrations or unpatched vulnerabilities. For more resources, check out our Spring EOL Resource Hub.

Stay secure. Stay supported. With HeroDevs.

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