Enterprise Edition: Improper Handling of Length Parameter Inconsistency
CVE-2026-14587 is a high-severity improper handling of length parameter inconsistency vulnerability in Enterprise Edition from Neo4j, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 2026.07, 5.26.29 as the first without the flaw, so updating Enterprise Edition to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.54% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Enterprise Edition to 2026.07 or 5.26.29, whichever matches your release line, or a later version.
- Update Community Edition to 2026.07 or 5.26.29, whichever matches your release line, or a later version.
- Update Neo4j to 5.26.29 or 2026.07.0, whichever matches your release line, or a later version.
- Read the advisory on neo4j.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Neo4j | Enterprise Edition | 2025.01 up to, but not including, 2026.07; 5.0 up to, but not including, 5.26.29 | 2026.07, 5.26.29 |
| Neo4j | Community Edition | 2025.01 up to, but not including, 2026.07; 5.0 up to, but not including, 5.26.29 | 2026.07, 5.26.29 |
| Neo4j | Neo4j | 5.0.0 up to, but not including, 5.26.29; 2025.01.0 up to, but not including, 2026.07.0 | 5.26.29, 2026.07.0 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 5.5 | Medium | CNA |
| CVSS 3.1 | 7.5 | High | NVD |
Official 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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Handling of Length Parameter Inconsistency
The product parses a formatted message or structure, but it does not handle or incorrectly handles a length field that is inconsistent with the actual length of the associated data.
How developers prevent this class of flaw
- When processing structured incoming data containing a size field followed by raw data, ensure that you identify and resolve any inconsistencies between the size field and the actual size of the data.
- Do not let the user control the size of the buffer.
- Validate that the length of the user-supplied data is consistent with the buffer size.
More Improper Handling of Length Parameter Inconsistency vulnerabilities (CWE-130)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Other vulnerabilities in Enterprise Edition
- 9.8 Critical severity
- 7.2 High severity
Recent Improper Handling of Length Parameter Inconsistency vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 8.7 High severity
- 7.5 High severity
- 8.6 High severity
- 7.8 High severity
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