The vulnerability stems from the MariaDB Connector/J driver truncating protocol unsigned 8‑byte length‑encoded integers to a Java int without ensuring the value fits a non‑negative bound. When a length greater than Integer.MAX_VALUE is received, the truncation can produce a negative or unexpectedly large value that downstream allocation and read logic uses. This can trigger NegativeArraySizeException, out‑of‑bounds read or write failures, or cause the client to allocate an oversized buffer, leading to crashes or resource exhaustion and thereby denying service to an application that relies on the driver.

MariaDB Connector/J, specifically the Java driver used to connect applications to MariaDB or MySQL databases. Versions from 3.0.0 up to, but not including, the fixed releases 3.3.7, 3.4.5, and 3.5.10 are vulnerable. Any Java application that incorporates these older driver jars is potentially affected.

With a CVSS score of 5.9 the flaw is considered moderate in severity. The EPSS score is not reported, and the vulnerability is not currently listed in the CISA KEV catalog, suggesting limited known exploitation. The likely attack vector is a malicious or compromised database server or a man‑in‑the‑middle attacker that can send a crafted packet to the client. If such an attacker succeeds, the client can experience crashes or memory exhaustion, interrupting service availability.