The vulnerability resides in PrefectHQ Prefect’s WebSocket endpoint (/api/events/in). Manipulating the request payload can trigger the route to skip authentication, resulting in an authentication bypass typified by CWE‑287 and CWE‑306. This flaw permits unauthenticated access to a live WebSocket channel, enabling an attacker to perform actions such as injecting real‑time instructions or exfiltrating data; these effects are inferred from the nature of the WebSocket channel but are not directly stated in the CVE. The flaw is confined to versions up to 3.6.13 and requires only a crafted HTTP request that can be sent from a remote host.

All installations of PrefectHQ Prefect version 3.6.13 or earlier are affected. The issue is tied to the WebSocket endpoint component and is fully resolved by upgrading to Prefect version 3.6.14 or later, which contains the commit f8afecadf88ea5f73694dafa3a365b9d8fae1ad6 that restores proper authentication checks.

The CVSS score of 6.9 indicates medium severity, and the vulnerability can be exploited remotely as the attack originates from outside the network. The EPSS score of less than 1% denotes a very low exploitation probability. However, the CVE explicitly reports that exploitation code has been published and may be used, increasing the urgency of patching. Because authentication is missing, an attacker can reach the Prefect server from outside the network without credentials.