CVE-2023-39743 in lrzip-next
Summary
by MITRE • 08/17/2023
lrzip-next LZMA v23.01 was discovered to contain an access violation via the component /bz3_decode_block src/libbz3.c.
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Analysis
by VulDB Data Team • 01/26/2026
The vulnerability identified as CVE-2023-39743 affects the lrzip-next LZMA compression library version 23.01, specifically within the bz3_decode_block function located in the src/libbz3.c source file. This represents a critical access violation flaw that can potentially lead to system instability and arbitrary code execution. The issue manifests when the library processes malformed or maliciously crafted input data through the decompression routine, creating a scenario where memory access occurs beyond allocated boundaries or to invalid memory regions. Such vulnerabilities are particularly dangerous in compression libraries since they often handle untrusted data from various sources including network streams, file uploads, or decompression of archived content.
The technical root cause of this vulnerability stems from insufficient input validation and memory boundary checking within the decompression algorithm. When the bz3_decode_block function processes compressed data, it fails to properly validate the structure and size constraints of the input stream before attempting to access memory locations. This lack of proper bounds checking creates an environment where an attacker can craft specially formatted compressed data that triggers the access violation. The vulnerability aligns with CWE-129, which addresses issues related to insufficient validation of length fields, and CWE-125, which covers out-of-bounds read conditions. The flaw represents a classic example of how improper input handling in cryptographic or compression routines can create exploitable conditions that allow attackers to manipulate memory access patterns.
From an operational perspective, this vulnerability poses significant risks to systems that utilize lrzip-next for data compression and decompression tasks. The impact extends across various deployment scenarios including file servers, backup systems, network appliances, and any application that relies on LZMA compression for data handling. Attackers could exploit this vulnerability by providing maliciously crafted compressed files that, when processed by the affected library, would cause the decompression routine to crash or potentially execute arbitrary code. The attack surface is broad since many applications and services depend on compression libraries for data handling, making this vulnerability particularly dangerous in environments where untrusted input is processed. The vulnerability also aligns with ATT&CK technique T1059.007, which covers command and scripting interpreter usage, as exploitation could potentially lead to command execution within the affected system.
Mitigation strategies for CVE-2023-39743 should prioritize immediate patching of the lrzip-next library to version 23.02 or later, which contains the necessary fixes for the access violation issue. Organizations should implement input validation measures to filter potentially malicious compressed data before processing, particularly in scenarios where untrusted inputs are handled. The implementation of memory safety techniques including address sanitizers and bounds checking can help detect and prevent exploitation attempts. Additionally, deployment of intrusion detection systems that monitor for unusual decompression activities or memory access patterns can provide early warning of potential exploitation attempts. Security teams should also consider implementing application whitelisting and sandboxing measures for applications that handle compressed data, reducing the potential impact of successful exploitation. Regular vulnerability assessments and penetration testing should be conducted to identify similar issues in other compression libraries and related components within the system infrastructure.