CVE-2021-45926 in MDB Tools
Summary
by MITRE • 01/01/2022
MDB Tools (aka mdbtools) 0.9.2 has a stack-based buffer overflow (at 0x7ffd0c689be0) in mdb_numeric_to_string (called from mdb_xfer_bound_data and _mdb_attempt_bind).
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Analysis
by VulDB Data Team • 01/05/2022
The vulnerability CVE-2021-45926 represents a critical stack-based buffer overflow flaw within MDB Tools version 0.9.2, a widely used open-source library for accessing microsoft access database files. This vulnerability specifically manifests within the mdb_numeric_to_string function which is invoked during database transfer operations through the mdb_xfer_bound_data and _mdb_attempt_bind functions. The buffer overflow occurs at memory address 0x7ffd0c689be0, indicating a classic stack corruption scenario where insufficient bounds checking allows malicious data to overwrite adjacent stack memory regions. The flaw exists in the handling of numeric data types when converting them to string representations, creating an exploitable condition that could be leveraged by attackers to execute arbitrary code or cause application crashes.
The technical implementation of this vulnerability stems from inadequate input validation within the numeric to string conversion process. When mdbtools processes database records containing numeric values, the mdb_numeric_to_string function fails to properly validate the size of the destination buffer before copying data. This oversight allows attackers to craft specially malformed database files or manipulate numeric data fields to exceed the allocated buffer space on the stack. The vulnerability is particularly concerning because it operates within core database processing functions that are routinely called during normal database operations, making exploitation possible through legitimate database access patterns rather than requiring specialized attack vectors.
Operationally, this vulnerability poses significant risks to systems utilizing MDB Tools for database processing, particularly in environments where untrusted database files are processed or where database connections are exposed to external data sources. The stack-based buffer overflow creates potential for remote code execution, denial of service attacks, or information disclosure depending on the specific exploitation scenario. Systems running applications that depend on mdbtools for database access, such as data migration tools, reporting applications, or database analysis utilities, could be compromised if they process untrusted mdb files. The impact extends beyond immediate system compromise to potential data corruption and unauthorized access to sensitive information stored within database environments. Organizations using this library in production environments face heightened risk during database processing operations, especially when handling external or unverified database content.
Mitigation strategies for CVE-2021-45926 should prioritize immediate patching of affected MDB Tools versions to the latest available releases that contain fixed buffer handling routines. System administrators should implement strict input validation measures and avoid processing untrusted database files through mdbtools applications. Network segmentation and access controls should be enforced to limit exposure of systems utilizing this library to potentially malicious data sources. The vulnerability aligns with CWE-121 stack-based buffer overflow classification and could be mapped to ATT&CK technique T1059.007 for command and control through application execution. Regular security assessments should include verification of mdbtools library versions and implementation of runtime protections such as stack canaries or address space layout randomization to reduce exploit reliability. Organizations should also consider implementing database file integrity checks and monitoring for unusual database processing patterns that might indicate exploitation attempts.