CVE-2026-119277 in MariaDB 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 3.5.11, decoders for OK packet session-state blocks, column definition packets, text row data, or binary row data used server-declared lengths without confirming that the requested bytes remained in the receive buffer. The decoders could position reads, create sub-buffers, or decode strings beyond the packet boundary. A malicious or compromised server, or a machine-in-the-middle attacker, could trigger unchecked ArrayIndexOutOfBoundsException or IllegalArgumentException failures inside JDBC calls and terminate connection handling. This issue is fixed in versions 3.3.7, 3.4.5, and 3.5.11.
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Analysis
by VulDB Data Team • 10/29/2026
MariaDB Connector/J serves as a critical bridge for Java-based applications seeking to interact with MariaDB and MySQL database systems, facilitating data exchange through standardized JDBC protocols. Within the affected version range spanning from 3.0.0 up to specific patched releases including 3.3.7, 3.4.5, and 3.5.11, a fundamental flaw exists in how the connector processes incoming network packets from the database server. The vulnerability centers on the decoders responsible for parsing OK packet session-state blocks, column definition packets, text row data, and binary row data. These components are tasked with interpreting variable-length fields where the protocol specifies that length information is provided by the sender rather than being fixed or self-delimitating in a way that prevents overflow.
The core technical deficiency lies in the failure to validate buffer boundaries before processing these server-declared lengths. When the connector receives packet data, it relies on the length values embedded within the packets to determine how many bytes to read and process. However, the implementation does not adequately verify whether the requested number of bytes actually remains available within the current receive buffer. This lack of boundary checking allows the decoder logic to position reads or create sub-buffers at memory locations that extend beyond the allocated packet boundaries. Consequently, if a malicious actor controls the server side or intercepts traffic in transit, they can craft packets with artificially inflated length fields that exceed the actual data payload size.
This architectural oversight leads directly to unchecked exceptions within the Java runtime environment. Specifically, attempting to access array indices outside their valid range triggers an ArrayIndexOutOfBoundsException, while invalid argument values passed to internal methods result in IllegalArgumentException failures. These unhandled exceptions cause the connection handling thread to terminate abruptly rather than gracefully closing or recovering from the error state. From a security operations perspective, this behavior constitutes a denial of service condition against the application layer. An attacker can exploit this flaw by sending malformed packets that force the JDBC driver to crash its processing threads, effectively disrupting database connectivity for any dependent services relying on those connections.
The attack vector is primarily classified as an input validation failure where untrusted data from the network stream dictates memory access patterns without sufficient sanitization or bounds checking. This aligns with Common Weakness Enumeration CWE-125, which describes Out-of-bounds Read vulnerabilities, and potentially CWE-787 for out-of-bounds write if internal state corruption occurs beyond simple exception throwing. In terms of adversarial tactics, this exploitation technique maps to the ATT&CK framework under Tactic TA0040 Impact, specifically relating to Denial of Service via service disruption or resource exhaustion through application crashes. The vulnerability highlights the risks associated with trusting protocol-level length fields without independent verification against actual buffer capacity, a common pitfall in high-performance network libraries that prioritize throughput over rigorous input validation.
Mitigation strategies require immediate upgrading to patched versions such as 3.3.7, 3.4.5, or 3.5.11 where the decoders have been updated to enforce strict boundary checks before processing variable-length data fields. Until patching is feasible, organizations should consider implementing network-level monitoring to detect anomalous packet sizes originating from database servers, although this is less effective against compromised internal hosts. Application-layer defenses such as circuit breakers or connection pool timeouts can help mitigate the operational impact by isolating failed connections and preventing cascading failures across the application infrastructure. Long-term remediation involves adopting a zero-trust approach to network protocols where all incoming data structures are validated for integrity and bounds compliance before being processed by core business logic, ensuring that even if an attacker manipulates packet lengths, the underlying memory safety mechanisms prevent exploitation.