CVE-2019-17543 in MySQL Server
Summary
by MITRE
LZ4 before 1.9.2 has a heap-based buffer overflow in LZ4_write32 (related to LZ4_compress_destSize), affecting applications that call LZ4_compress_fast with a large input. (This issue can also lead to data corruption.) NOTE: the vendor states "only a few specific / uncommon usages of the API are at risk."
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Analysis
by VulDB Data Team • 07/16/2025
The vulnerability CVE-2019-17543 represents a critical heap-based buffer overflow within the LZ4 compression library version 1.9.2 and earlier, specifically affecting the LZ4_write32 function during LZ4_compress_destSize operations. This flaw manifests when applications utilize the LZ4_compress_fast function with substantial input data, creating conditions where memory boundaries are exceeded during compression processes. The vulnerability stems from inadequate input validation and buffer size calculations within the compression algorithm implementation, allowing maliciously crafted input data to overwrite adjacent memory regions in the heap. The issue is particularly concerning because it can result in arbitrary code execution or data corruption, depending on the specific memory layout and the nature of the overflow.
The technical implementation of this vulnerability resides in the memory management aspects of the LZ4 compression library where the LZ4_write32 function fails to properly validate the size of data being written to memory buffers. This function, which is part of the core compression logic, does not perform adequate bounds checking when dealing with large input data sets, particularly when the destination buffer size is constrained. The flaw aligns with CWE-121, heap-based buffer overflow, and demonstrates characteristics consistent with CWE-787, out-of-bounds write, where insufficient validation allows data to be written beyond the allocated buffer boundaries. The specific conditions that trigger this vulnerability involve calling LZ4_compress_fast with inputs that cause the compression algorithm to attempt writing more data than the destination buffer can accommodate, creating a scenario where adjacent heap memory becomes corrupted.
The operational impact of CVE-2019-17543 extends beyond simple data corruption, presenting significant security risks to systems that rely on LZ4 compression for data processing and transmission. Applications that process large files, handle network data streams, or utilize compression in security-sensitive contexts become vulnerable to potential exploitation, where attackers could craft inputs designed to trigger the buffer overflow and execute arbitrary code within the application's memory space. This vulnerability affects a wide range of software systems including web servers, database management systems, network appliances, and any application that incorporates LZ4 compression functionality. The risk assessment must consider that while the vendor indicates only "a few specific/uncommon usages" are at risk, the widespread adoption of LZ4 compression across numerous applications and platforms means that many systems could potentially be affected, particularly those handling large data inputs or operating in security-sensitive environments.
Mitigation strategies for CVE-2019-17543 primarily focus on upgrading to LZ4 version 1.9.2 or later, where the buffer overflow vulnerability has been addressed through improved bounds checking and memory management. Organizations should conduct comprehensive vulnerability assessments to identify all systems and applications that utilize LZ4 compression libraries, particularly those handling large input data or operating in environments where input validation is insufficient. The remediation process should include not only updating the LZ4 library but also implementing additional input validation measures at the application level to prevent malformed data from reaching the compression functions. Security teams should consider implementing runtime protections such as address space layout randomization and stack canaries, along with monitoring for anomalous memory access patterns that could indicate exploitation attempts. Additionally, developers should follow secure coding practices by implementing proper input validation, bounds checking, and memory allocation verification when integrating compression libraries into their applications, aligning with ATT&CK technique T1070.004 for indicator removal and T1059.001 for command and scripting interpreter to prevent exploitation through memory corruption attacks.