CVE-2018-6541 in ZZIPlib
Summary
by MITRE
In ZZIPlib 0.13.67, there is a bus error caused by loading of a misaligned address (when handling disk64_trailer local entries) in __zzip_fetch_disk_trailer (zzip/zip.c). Remote attackers could leverage this vulnerability to cause a denial of service via a crafted zip file.
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Analysis
by VulDB Data Team • 07/10/2025
The vulnerability identified as CVE-2018-6541 affects ZZIPlib version 0.13.67, a library used for reading zip archives in various applications and systems. This issue represents a critical memory access problem that occurs during the processing of zip file structures, specifically when handling disk64_trailer local entries within the zip file format. The flaw manifests as a bus error resulting from improper memory alignment during the __zzip_fetch_disk_trailer function execution in the zzip/zip.c source file. The root cause lies in how the library handles memory access patterns when processing certain zip file metadata structures, particularly those related to the Zip64 extension format that allows for larger archive sizes beyond traditional 32-bit limits.
This vulnerability operates at the intersection of memory management and file format parsing, creating a scenario where remote attackers can exploit malformed zip files to trigger system crashes. The technical implementation involves the library attempting to access memory addresses that are not properly aligned for the target architecture, leading to bus errors that cause the application to terminate unexpectedly. The flaw specifically targets the disk64_trailer processing logic, which is part of the Zip64 specification designed to handle archives larger than 4GB. When a maliciously crafted zip file contains improperly formatted disk64_trailer entries, the library's memory access patterns become invalid, resulting in system-level crashes rather than graceful error handling.
The operational impact of this vulnerability extends beyond simple denial of service, as it can be exploited by remote attackers to disrupt services that rely on ZZIPlib for zip file processing. Applications using this library may become unavailable to legitimate users when processing malicious zip files, potentially affecting web services, file upload systems, and any software that handles user-provided zip archives. The vulnerability affects systems where ZZIPlib is integrated as a dependency, including various content management systems, file sharing platforms, and applications that support zip file extraction. This creates a significant risk for service availability and can be leveraged as part of broader attack strategies targeting system reliability and uptime.
The vulnerability aligns with CWE-121, which addresses stack-based buffer overflow conditions, and more specifically with CWE-129, concerning improper validation of array indices. From an ATT&CK framework perspective, this represents a denial of service technique that can be categorized under T1499.004 for Network Denial of Service. The exploitation requires minimal privileges since it operates at the application level rather than requiring system-level access. Mitigation strategies include immediate patching of ZZIPlib to version 0.13.68 or later, which contains the necessary memory alignment fixes. Additionally, implementing proper input validation and sanitization of zip file contents before processing can help prevent exploitation. Organizations should also consider deploying network monitoring solutions to detect unusual zip file processing patterns and implement application-level restrictions on zip file handling where possible.