CVE-2023-39741 in lrzip
Summary
by MITRE • 08/17/2023
lrzip v0.651 was discovered to contain a heap overflow via the libzpaq::PostProcessor::write(int) function at /libzpaq/libzpaq.cpp. This vulnerability allows attackers to cause a Denial of Service (DoS) via a crafted file.
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Analysis
by VulDB Data Team • 01/26/2026
The vulnerability identified as CVE-2023-39741 affects lrzip version 0.651 and represents a critical heap overflow condition within the libzpaq library component. This issue manifests specifically within the libzpaq::PostProcessor::write(int) function located at /libzpaq/libzpaq.cpp, where improper input validation and memory management practices create exploitable conditions that can be leveraged by malicious actors. The vulnerability resides in the software's handling of compressed data streams and demonstrates a classic buffer management flaw that can lead to unpredictable system behavior and potential security compromise.
The technical implementation of this heap overflow occurs when the PostProcessor::write function processes integer parameters without adequate bounds checking or memory allocation verification. This flaw falls under the CWE-121 heap-based buffer overflow category, where insufficient memory bounds checking allows an attacker to write data beyond the allocated heap memory region. The vulnerability specifically targets the libzpaq library which is used for data compression and decompression operations within the lrzip toolchain, making it a critical component in the overall attack surface. When a maliciously crafted file is processed through this function, the overflow can corrupt adjacent heap memory, leading to application instability and potential code execution.
The operational impact of CVE-2023-39741 manifests primarily as a Denial of Service condition that can effectively render the affected system or application unusable. Attackers can exploit this vulnerability by crafting specially formatted files that trigger the heap overflow during decompression or processing operations, causing the lrzip application to crash or behave unpredictably. This DoS condition can be particularly damaging in automated environments where lrzip is used for regular data processing tasks, as it can lead to service interruptions and system downtime. The vulnerability can also potentially be leveraged as a stepping stone in more sophisticated attacks, as heap corruption often creates opportunities for privilege escalation or information disclosure attacks, though the primary impact remains focused on service disruption.
Mitigation strategies for this vulnerability should prioritize immediate patching of the lrzip software to version 0.652 or later, which contains the necessary fixes for the heap overflow condition. System administrators should implement strict file validation procedures for any data processed through lrzip, including content scanning and file type verification before decompression operations. The implementation of memory safety controls such as address space layout randomization and stack canaries can provide additional defense-in-depth measures against exploitation attempts. Organizations should also consider implementing monitoring solutions to detect unusual processing patterns that might indicate exploitation attempts, while following ATT&CK framework guidance for detecting and preventing heap-based memory corruption attacks. Regular security assessments and vulnerability scanning should be conducted to identify similar issues in other components of the system that might utilize similar memory management patterns, ensuring comprehensive protection against related threats.