CVE-2018-14564 in THULAC
Summary
by MITRE
An issue was discovered in libthulac.so in THULAC through 2018-02-25. A SEGV can occur in NGramFeature::find_bases in include/cb_ngram_feature.h.
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Analysis
by VulDB Data Team • 04/25/2023
The vulnerability identified as CVE-2018-14564 represents a critical memory access violation within the THULAC (Thai University Lexical Analysis Corpus) natural language processing library. This issue affects versions of the library released through February 25, 2018, and specifically targets the libthulac.so shared library component. The flaw manifests as a segmentation fault during the execution of the NGramFeature::find_bases function located in the include/cb_ngram_feature.h header file, indicating a fundamental weakness in how the library handles memory operations during n-gram feature processing.
The technical root cause of this vulnerability stems from improper memory management within the n-gram feature extraction mechanism. When the NGramFeature::find_bases function processes linguistic data, it appears to access memory locations that have not been properly allocated or validated, leading to a segmentation violation. This type of flaw falls under the CWE-125 vulnerability category, which specifically addresses out-of-bounds read conditions where programs access memory locations beyond the intended buffer boundaries. The vulnerability represents a classic example of memory safety issues that can be exploited to cause application crashes or potentially enable more sophisticated attacks depending on the execution context.
The operational impact of this vulnerability extends beyond simple application instability, as it can be leveraged to disrupt services that depend on THULAC for text processing tasks. Systems utilizing this library for natural language understanding, information retrieval, or text analysis may experience unexpected termination when processing certain input data that triggers the memory access violation. This presents a significant risk for production environments where reliability and uptime are critical, particularly in applications such as chatbots, automated content analysis systems, or linguistic research platforms that rely on consistent processing of text data. The vulnerability can be classified under ATT&CK technique T1499.004, which covers network denial of service attacks through resource exhaustion or application crashes, as the segmentation fault can effectively terminate service availability.
Mitigation strategies for CVE-2018-14564 should prioritize immediate patching of affected systems by upgrading to a version of THULAC that addresses this memory access issue. Organizations should implement comprehensive input validation measures to prevent malformed data from triggering the vulnerable code path, while also establishing monitoring systems to detect unusual application termination patterns. The fix should involve proper bounds checking within the NGramFeature::find_bases function to ensure all memory accesses are validated before execution. Additionally, system administrators should consider implementing sandboxing or containerization techniques to isolate applications using THULAC, thereby limiting the potential impact of any exploitation attempts. Regular security assessments of third-party libraries should be conducted to identify similar vulnerabilities, and automated vulnerability scanning tools should be employed to detect instances of the affected library version within the organization's infrastructure.