CVE-2018-5747 in Long Range Zip
Summary
by MITRE
In Long Range Zip (aka lrzip) 0.631, there is a use-after-free in the ucompthread function (stream.c). Remote attackers could leverage this vulnerability to cause a denial of service via a crafted lrz file.
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Analysis
by VulDB Data Team • 02/02/2023
The vulnerability identified as CVE-2018-5747 affects Long Range Zip version 0.631 and represents a critical use-after-free condition within the ucompthread function located in the stream.c source file. This type of memory safety issue occurs when a program continues to reference memory locations after they have been freed, creating potential avenues for exploitation that can lead to system instability or malicious code execution. The vulnerability specifically manifests during the decompression process when handling crafted lrz files, making it particularly dangerous in environments where untrusted data processing is required.
The technical flaw stems from improper memory management within the compression library's threading implementation. When the ucompthread function processes compressed data streams, it fails to properly validate or manage memory references, allowing attackers to craft malicious lrz files that trigger the use-after-free scenario. This condition can be exploited remotely through the processing of specially crafted archive files, where the attacker controls the input data that flows through the vulnerable code path. The flaw is categorized under CWE-416 as a Use After Free vulnerability, which represents one of the most common and dangerous classes of memory safety issues in software applications.
The operational impact of this vulnerability extends beyond simple denial of service, as it provides potential attackers with opportunities to execute arbitrary code or cause system crashes that could be leveraged in broader attack scenarios. Remote exploitation capabilities make this particularly concerning for web services, file processing systems, or any application that handles user-provided compressed files without proper validation. The vulnerability affects systems that utilize lrzip for decompression operations, potentially compromising servers, desktop applications, or embedded systems that process compressed data. According to ATT&CK framework category T1203, this vulnerability could be exploited as part of a broader attack chain targeting system resources and memory management components.
Mitigation strategies for CVE-2018-5747 include immediate patching of lrzip to version 0.632 or later, which contains the necessary memory management fixes. Organizations should also implement strict input validation and sanitization for all compressed file processing, particularly when handling untrusted data from external sources. Additional defensive measures include deploying network segmentation to limit exposure, implementing file type restrictions, and monitoring for unusual file processing patterns that might indicate exploitation attempts. The vulnerability highlights the importance of thorough memory management testing and the implementation of modern security practices such as address sanitizers, stack canaries, and heap metadata protection mechanisms to prevent similar issues in future software development cycles.