What’s Vulnerable › Vulnerabilities
CVE-2026-14587: Unathenticated connection can hold Bolt channel open
- Severity: high (CVSS 7.5 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.5% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-08-05 · updated 2026-08-28
- Weakness: CWE-130
Description
Neo4j's 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. Because the same unread bytes remain at the front of the decoder buffer, appending a terminating byte later does not recover the connection. The decoder re-reads the same first 32 continuation bytes, returns without producing a handshake-finalization message, and leaves the channel open. This can be triggered before authentication by any client that can reach the Bolt connector.
Affected products
- Neo4j: from 5.0.0 before 5.26.29; from 2025.01.0 before 2026.07.0 — fixed in 2026.07.0, 5.26.29
How to fix
Upgrade to a fixed version: Neo4j 2026.07.0, 5.26.29. Check the vendor advisory for mitigations.
References
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