CVE-2026-14587 neo4j CVE debrief

Who should care

Organizations using Neo4j with the Bolt connector should be aware of this vulnerability and take steps to mitigate it. This includes reviewing and applying vendor remediation, verifying that the Bolt connector is properly configured and secured, and monitoring for potential exploitation attempts. Security teams and vulnerability management teams should prioritize this issue based on the CVSS score of 5.5 and the potential for unauthenticated clients to trigger the issue.

Technical summary

The Neo4j Bolt modern handshake decoder treats an overlong capability bit mask the same way it treats a truncated bit mask. When an unauthenticated client sends a selected protocol version followed by 32 continuation bytes in the capability mask, the decoder resets the reader index and waits for more bytes instead of rejecting the protocol message and closing the channel. This can cause the decoder to enter an infinite loop, consuming system resources. The issue can be triggered before authentication by any client that can reach the Bolt connector.

Defensive priority

Medium priority given the CVSS score of 5.5 and the potential for unauthenticated clients to trigger the issue.

Recommended defensive actions

• Review and apply vendor remediation for CVE-2026-14587
• Verify that the Bolt connector is properly configured and secured
• Monitor for potential exploitation attempts
• Implement compensating controls to detect and prevent similar attacks
• Conduct a thorough review of the Bolt connector configuration and ensure that it is properly secured
• Perform regular security audits to identify potential vulnerabilities
• Track and analyze logs to detect potential exploitation attempts

Evidence notes

Evidence from the NVD and CVE.org indicates that an unauthenticated client can trigger the issue by sending a selected protocol version followed by 32 continuation bytes in the capability mask. The decoder resets the reader index and waits for more bytes instead of rejecting the protocol message and closing the channel. This behavior can lead to a denial-of-service (DoS) condition. Defenders should verify the Bolt connector configuration and ensure that it is properly secured.

Official resources