ArcadeDB versions 21.12.1 through 26.10.1 include an authorization bypass that lets users with readRecord permission overwrite the shared GraphQL schema via the read‑only /api/v1/query/{database} endpoint. By sending a GraphQL type definition containing a malicious @sql directive, an attacker can change the schema that all users, including administrators, use to resolve queries. This endows the attacker with the ability to manipulate data returned to other users, compromising confidentiality, integrity, and potentially allowing further privilege escalation if the manipulated schema causes increased data exposure or unintended logic execution.

The vulnerability affects ArcadeData ArcadeDB distributions released between version 21.12.1 and the 26.10.1 release. Users running any of these versions are susceptible to the schema replacement attack if fewer than proper restrictions on readRecord access are in place.

The CVSS score of 5.3 indicates moderate severity, and the EPSS score is not available. The vulnerability is not listed in CISA's KEV catalog. Exploitation requires only readRecord permissions and use of the publicly exposed /api/v1/query endpoint, making the attack vector local to the database cluster but accessible over the network if the endpoint is exposed. Because the exploit is a simple HTTP POST with crafted payload, it can be performed by any authenticated user with read access, making the risk moderate if the database is reachable from untrusted networks.