CVE-2021-33451 in lrzip
Summary
by MITRE • 07/26/2022
An issue was discovered in lrzip version 0.641. There are memory leaks in fill_buffer() in stream.c.
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Analysis
by VulDB Data Team • 08/27/2022
The vulnerability identified as CVE-2021-33451 affects lrzip version 0.641 and represents a memory leak condition within the fill_buffer() function located in stream.c. This issue manifests during the processing of compressed data streams where the application fails to properly release allocated memory resources, leading to gradual memory consumption over time. The lrzip utility is a compression tool designed for handling large files with high compression ratios, commonly used in environments where efficient data storage and transmission are critical. When operating with malformed or specially crafted input data, the memory leak becomes exploitable, potentially leading to resource exhaustion and system instability.
The technical flaw resides in the stream.c source file where the fill_buffer() function does not adequately manage memory allocation and deallocation cycles. This function is responsible for reading and buffering data during compression or decompression operations, and the improper handling of memory resources results in allocated memory blocks that remain unreleased even after their intended use has concluded. The vulnerability specifically impacts the stream processing logic where temporary buffers are allocated to handle data chunks but are not properly freed when the processing completes or when errors occur during buffer operations. This type of memory management error falls under the category of memory leak vulnerabilities as defined by CWE-401, which specifically addresses the failure to release memory resources after their use has concluded.
The operational impact of this vulnerability extends beyond simple resource consumption issues, as it can lead to significant system degradation and potential denial of service conditions. When applications utilizing lrzip process large volumes of data over extended periods, the cumulative effect of unreleased memory can cause system performance degradation, application crashes, or complete system instability. The vulnerability is particularly concerning in server environments or automated processing systems where continuous operation is expected, as the memory leaks will progressively consume available system resources. Attackers could potentially exploit this by providing maliciously crafted input files that trigger the memory leak condition repeatedly, causing gradual system resource exhaustion and service disruption.
Mitigation strategies for CVE-2021-33451 should prioritize immediate patching of affected lrzip installations to version 0.642 or later, which contains the necessary memory management fixes. System administrators should also implement monitoring solutions to track memory usage patterns in applications utilizing lrzip, enabling early detection of potential exploitation attempts. Additionally, input validation and sanitization measures should be implemented to prevent processing of malformed or unexpected data streams. Organizations should consider implementing resource limits and monitoring for processes using lrzip to prevent complete system exhaustion. The vulnerability demonstrates the importance of proper memory management in security-critical applications and aligns with ATT&CK technique T1499.004 which covers network denial of service attacks through resource exhaustion. Regular security audits and code reviews focusing on memory management practices should be conducted to identify similar vulnerabilities in other software components, particularly those handling streaming data or large file operations.