CVE-2008-5031 in Python
Summary
by MITRE
Multiple integer overflows in Python 2.2.3 through 2.5.1, and 2.6, allow context-dependent attackers to have an unknown impact via a large integer value in the tabsize argument to the expandtabs method, as implemented by (1) the string_expandtabs function in Objects/stringobject.c and (2) the unicode_expandtabs function in Objects/unicodeobject.c. NOTE: this vulnerability reportedly exists because of an incomplete fix for CVE-2008-2315.
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Analysis
by VulDB Data Team • 08/27/2019
The vulnerability described in CVE-2008-5031 represents a critical integer overflow issue affecting multiple versions of the Python programming language from 2.2.3 through 2.5.1 and 2.6. This flaw specifically manifests within the expandtabs method implementation where improper handling of large integer values in the tabsize argument creates conditions that can lead to unpredictable system behavior. The vulnerability is particularly concerning because it affects core string manipulation functions that are widely used throughout Python applications and systems, making it a significant threat to software security and stability. The issue stems from incomplete remediation of a previous vulnerability identified as CVE-2008-2315, indicating that the fix for the initial problem was insufficient and left residual security weaknesses in the codebase.
The technical implementation of this vulnerability occurs within the stringobject.c and unicodeobject.c source files where the string_expandtabs and unicode_expandtabs functions process tabsize parameters without proper bounds checking or overflow protection mechanisms. When attackers provide excessively large integer values to these functions, the arithmetic operations involved in calculating expanded string lengths can exceed the maximum representable value for the integer data type, causing integer overflow conditions. This overflow can result in negative values, truncated calculations, or memory corruption that may be exploited to manipulate program flow or access unauthorized memory regions. The vulnerability operates in a context-dependent manner, meaning that exploitation requires specific conditions and attacker control over input data, but once triggered, can lead to various security consequences including denial of service, memory corruption, or potentially arbitrary code execution.
The operational impact of CVE-2008-5031 extends beyond simple program crashes or instability, as it can provide attackers with opportunities to compromise system integrity and availability. Systems running vulnerable Python versions that process user-provided data through string manipulation operations become susceptible to exploitation, particularly in web applications, network services, or any environment where Python handles untrusted input. The vulnerability's presence in core string handling functions means that even seemingly innocuous operations like text processing, log file generation, or data formatting could become attack vectors. Given that Python is widely used across various platforms and applications, the potential attack surface for this vulnerability is extensive, making it a critical concern for system administrators and security professionals managing Python-based environments.
The vulnerability aligns with CWE-190, which specifically addresses integer overflow conditions, and represents a classic example of incomplete patch management where a previous fix for a similar issue was deemed insufficient. From an ATT&CK perspective, this vulnerability could be leveraged as part of a broader attack chain, potentially serving as an initial access point or privilege escalation vector when combined with other exploitation techniques. Organizations should prioritize immediate patching of affected Python versions to address this vulnerability, as the incomplete nature of the previous fix demonstrates that security remediation requires comprehensive analysis and testing. The vulnerability also highlights the importance of proper input validation and integer bounds checking in security-critical code paths, particularly in language implementations where core functions handle potentially untrusted data from external sources.