CVE-2026-119279 in Connector
Summary
by MITRE • 10/29/2026
MariaDB Connector/J is used to connect applications developed in Java to MariaDB and MySQL databases. From 3.0.0 until 3.3.7, 3.4.5, and 3.5.10, the ReadableByteBuf.readLength() and ReadableByteBuf.readIntLengthEncodedNotNull() methods narrowed the protocol's unsigned 8-byte length-encoded integer to a Java int without checking that the value fit a non-negative integer. Values above Integer.MAX_VALUE could wrap to a negative or unrelated length that downstream allocation and read paths used. A malicious or compromised server, or a machine-in-the-middle attacker, could trigger NegativeArraySizeException, out-of-bounds failures, or oversized allocation behavior in client connection handling. This issue is fixed in versions 3.3.7, 3.4.5, and 3.5.10.
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Analysis
by VulDB Data Team • 10/29/2026
MariaDB Connector/J serves as the critical bridge allowing Java-based applications to communicate with MariaDB and MySQL database servers, facilitating data exchange through a specific binary protocol. Within versions ranging from 3.0.0 up to 3.3.7, 3.4.5, and 3.5.10, a significant implementation flaw exists in the handling of length-encoded integers during the parsing phase of network traffic processing. The vulnerability centers on two specific methods within the ReadableByteBuf class: readLength() and readIntLengthEncodedNotNull(). These functions are responsible for interpreting variable-length integer fields sent by the database server to indicate the size or structure of subsequent data payloads. In a correctly implemented parser, these unsigned 8-byte length-encoded integers must be validated against the constraints of the host language's primitive types before conversion. However, in the affected versions, the code performs a direct narrowing cast from the larger protocol integer type directly into a Java int without verifying whether the value falls within the range of a non-negative signed 32-bit integer.
This lack of validation allows values exceeding Integer.MAX_VALUE to wrap around or be interpreted as negative numbers due to two's complement representation rules inherent in Java integers. When such an invalid length is processed, downstream components that rely on this value for memory allocation and buffer reading operations receive corrupted instructions. Specifically, if the wrapped value results in a large positive integer beyond available heap space, it triggers massive oversized allocation behavior which can rapidly exhaust system resources. Alternatively, if the wrapping produces a negative number or zero, subsequent array creation attempts fail with NegativeArraySizeException errors because Java arrays cannot have negative dimensions. These failures manifest as out-of-bounds exceptions or abrupt termination of the connection handling thread, effectively disrupting normal application operation and potentially causing denial of service conditions for users attempting to interact with the database.
The operational impact of this vulnerability is severe due to its potential exploitation vectors. A malicious actor controlling a compromised MariaDB server can craft specific responses containing oversized length fields to trigger these exceptions in connecting clients. Similarly, an attacker performing a machine-in-the-middle attack could intercept and modify protocol traffic to inject malformed length values into the stream directed at the client application. The resulting instability leads to crashes or unhandled exceptions within the Java Virtual Machine environment hosting the connector. This not only disrupts service availability but may also expose internal stack traces or error details that aid further reconnaissance by an attacker, although the primary immediate risk is denial of service through resource exhaustion or thread termination.
From a classification perspective, this vulnerability aligns with CWE-190 Integer Overflow or Wraparound and CWE-787 Out-of-bounds Write if the corrupted length leads to memory corruption in lower-level buffers, though primarily it results in logical errors leading to exceptions under CWE-253 Incorrect Check of Function Return Value. In terms of attack patterns, this relates to MITRE ATT&CK technique T1499 Endpoint Denial of Service where an attacker leverages application logic flaws to degrade system availability. The root cause is a failure to enforce input validation constraints on data received from external sources, which violates the principle of least privilege and robust error handling expected in secure coding standards such as OWASP Software Verification Controls.
To mitigate this risk, organizations must immediately upgrade MariaDB Connector/J to version 3.3.7, 3.4.5, or 3.5.10 where these validation checks have been implemented. Developers should ensure that their build pipelines enforce dependency updates for all Java applications relying on database connectivity libraries. Additionally, implementing network-level monitoring can help detect anomalous traffic patterns indicative of exploitation attempts targeting known vulnerable versions until patches are fully deployed across the infrastructure. Regular auditing of third-party library dependencies is essential to prevent similar issues arising from unchecked data type conversions in other components of the software supply chain.