CVE-2010-1666 in python-cjson
Summary
by MITRE
Buffer overflow in Dan Pascu python-cjson 1.0.5, when UCS-4 encoding is enabled, allows context-dependent attackers to cause a denial of service (application crash) or possibly have unspecified other impact via vectors involving crafted Unicode input to the cjson.encode function.
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Analysis
by VulDB Data Team • 01/26/2025
The vulnerability identified as CVE-2010-1666 represents a critical buffer overflow condition within the python-cjson library version 1.0.5, specifically manifesting when UCS-4 encoding is activated. This flaw resides in the cjson.encode function's handling of Unicode input data, creating a scenario where maliciously crafted Unicode sequences can trigger unexpected behavior in applications utilizing this library. The vulnerability operates through a fundamental memory management issue where insufficient bounds checking occurs during the encoding process when dealing with wide character representations. The buffer overflow vulnerability classifies under CWE-121, which specifically addresses stack-based buffer overflow conditions that occur when insufficient checks are performed on the size of data being copied into fixed-length buffers. This particular implementation flaw demonstrates how encoding-specific configurations can create unexpected attack vectors within seemingly benign data processing functions.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially encompass more severe consequences including arbitrary code execution or system instability. When applications process Unicode input through the affected cjson.encode function with UCS-4 encoding enabled, the buffer overflow can cause application crashes, leading to service disruption and potential denial of service attacks against systems relying on this library. The context-dependent nature of the attack means that exploitation requires specific conditions including the presence of UCS-4 encoding and the injection of carefully crafted Unicode sequences that exceed buffer boundaries. Attackers can leverage this vulnerability by providing malicious input that, when processed through the vulnerable encoding function, overflows memory buffers and potentially corrupts adjacent memory regions. The vulnerability demonstrates characteristics consistent with ATT&CK technique T1059.007, which involves the use of scripting languages to execute malicious code, particularly when applications process untrusted input through vulnerable library functions.
Mitigation strategies for CVE-2010-1666 require immediate attention through library version updates and input validation measures. System administrators should prioritize upgrading to python-cjson versions that have addressed this buffer overflow vulnerability, as the original 1.0.5 release contains no known patches. Organizations should implement strict input validation protocols that sanitize Unicode data before processing through JSON encoding functions, particularly when UCS-4 encoding is enabled. Additionally, runtime protections such as stack canaries, address space layout randomization, and non-executable stack segments can provide additional defense-in-depth measures against exploitation attempts. The vulnerability highlights the importance of thorough security testing for encoding-specific functionality and demonstrates how seemingly innocuous library configuration options can create significant security risks. Security monitoring should include detection of unusual JSON processing patterns and potential buffer overflow indicators, while regular security assessments of third-party library dependencies should be conducted to identify similar vulnerabilities across the application stack. The incident underscores the necessity of maintaining up-to-date security patches and implementing comprehensive input sanitization practices to prevent exploitation of memory corruption vulnerabilities in widely-used library components.