CVE-2018-13843 in HTSlib
Summary
by MITRE
An issue has been found in HTSlib 1.8. It is a memory leak in bgzf_getline in bgzf.c.
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Analysis
by VulDB Data Team • 08/05/2024
The vulnerability identified as CVE-2018-13843 represents a critical memory management flaw within HTSlib version 1.8, specifically affecting the bgzf_getline function in the bgzf.c source file. This memory leak occurs during the processing of BGZF (Blocked GNU Zip Format) compressed data streams, which are commonly used in bioinformatics applications for handling large genomic datasets. The issue manifests when the bgzf_getline function fails to properly release allocated memory resources after processing compressed data, leading to gradual memory consumption over time. This type of vulnerability falls under the category of memory leak defects classified by CWE-401 as "Improper Release of Memory Before Removing Last Reference" and represents a fundamental failure in resource management within the library's decompression routines.
The technical implementation of this vulnerability stems from the bgzf_getline function's handling of internal buffers and memory allocations during the decompression process. When processing compressed data streams, the function allocates memory for temporary buffers to hold decompressed content, but fails to consistently free this memory when the function completes its operation or encounters certain error conditions. This memory leak becomes particularly problematic in long-running applications or batch processing scenarios where HTSlib is repeatedly called to process multiple BGZF files or streams. The vulnerability is classified under the ATT&CK technique T1070.004 "File and Directory Permissions Modification" in the context of resource exhaustion attacks, where attackers can exploit the memory leak to consume system resources and potentially cause denial of service conditions.
The operational impact of CVE-2018-13843 extends beyond simple resource consumption, as it can severely affect the performance and stability of bioinformatics applications that rely on HTSlib for processing genomic data. Applications using affected versions may experience progressive memory degradation, leading to system instability, application crashes, or complete system resource exhaustion. This is particularly concerning in high-throughput sequencing environments where large numbers of genomic files are processed sequentially, as the cumulative effect of memory leaks can quickly overwhelm system resources. The vulnerability affects any application that utilizes the bgzf_getline function for reading compressed data, including but not limited to variant calling pipelines, alignment tools, and genomic data analysis platforms. Organizations running these applications may observe increasing memory usage patterns over time, which can be difficult to diagnose without proper monitoring tools, making this vulnerability particularly insidious in production environments.
Mitigation strategies for CVE-2018-13843 primarily involve upgrading to HTSlib version 1.9 or later, where the memory leak has been addressed through proper memory management practices. System administrators should implement regular monitoring of memory consumption in applications utilizing HTSlib to detect potential exploitation of this vulnerability. Additionally, organizations should consider implementing process isolation and resource limits for bioinformatics applications to prevent complete system exhaustion. The fix implemented in newer versions typically involves ensuring that all allocated memory within the bgzf_getline function is properly freed regardless of execution path, addressing the root cause of the memory leak through improved resource management and defensive programming practices. This vulnerability demonstrates the importance of proper memory management in cryptographic and data processing libraries, where resource exhaustion can have cascading effects on system stability and security.