Network Utility Vulnerability in ToolHive by StackLok
CVE-2026-54450

2.9LOW

Key Information:

Vendor

Stacklok

Status
Toolhive
Vendor
CVE Published:
15 September 2026

What is CVE-2026-54450?

ToolHive, a utility for managing Model Context Protocol (MCP) servers, has a vulnerability in its networking configuration that fails to recognize certain IPv6 NAT64 prefixes as private. This flaw allows an attacker to exploit classifications of private IP addresses as public, creating a pathway for probing internal TCP or TLS connections. The vulnerability specifically arises when an external OAuth client sends a malicious client_id URL, triggering processes that inadvertently allow routing through unsecured paths. Users of ToolHive behind a NAT64/DNS64 gateway are particularly at risk as it can lead to unauthorized internal reachability exploration. The issue has been resolved in version 0.29.1, emphasizing the importance of keeping software updated.

Affected Version(s)

toolhive < 0.29.1

References

https://github.com/stacklok/toolhive/security/advisories/...
x_refsource_CONFIRM
https://github.com/stacklok/toolhive/commit/26912af453d20...
x_refsource_MISC
https://github.com/stacklok/toolhive/releases/tag/v0.29.1
x_refsource_MISC

CVSS V4

Score:
2.9
Severity:
LOW
Confidentiality:
Low
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
Physical
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.