NullHub versions up to 2026.5.29 contain a flaw where the authentication token for the management API defaults to null and is never set, allowing any user to send requests without an Authorization header or Origin header to endpoints exposed on non‑loopback interfaces. Attackers exploiting this can control agent instances, overwrite configuration files—including provider credentials—and manipulate cron jobs and MCP servers, effectively gaining full control of the host and any applications running on it.

The affected product is NullHub by nullclaw, specifically all releases through and including version 2026.5.29. No other versions or products were listed as impacted.

The CVSS score of 9.2 underscores the critical severity, and the EPSS score of 0.81% indicates a low but non‑zero likelihood of exploitation, while the lack of authentication combined with network‑exposed endpoints means the vulnerability could be exploited by any unauthenticated actor on the network. The vulnerability is not yet listed in CISA’s KEV catalog, but it presents a high risk of remote code execution or privilege escalation through unauthenticated API access.