CVE-2019-13232 in UnZIP
Summary
by MITRE
Info-ZIP UnZip 6.0 mishandles the overlapping of files inside a ZIP container, leading to denial of service (resource consumption), aka a "better zip bomb" issue.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 05/21/2025
The vulnerability identified as CVE-2019-13232 affects Info-ZIP UnZip version 6.0 and represents a critical resource consumption issue that manifests through improper handling of overlapping files within ZIP archive containers. This flaw enables attackers to craft malicious ZIP files that can cause significant system resource exhaustion when processed by the affected unzip utility. The vulnerability operates by exploiting the way UnZip manages file overlaps during extraction, creating a scenario where the decompression process consumes excessive memory and processing resources. This particular issue has been categorized as a "better zip bomb" due to its enhanced capability to amplify resource consumption compared to traditional zip bomb attacks, making it particularly dangerous for systems that automatically process or validate ZIP files without proper safeguards.
The technical root cause of this vulnerability lies in the improper validation and handling of overlapping file entries within ZIP archives. When UnZip encounters overlapping file structures, it fails to properly manage the memory allocation and processing resources required for extraction. This flaw stems from inadequate boundary checking and resource management during the decompression process, allowing maliciously crafted archives to trigger excessive memory allocation patterns. The vulnerability specifically manifests when multiple files within a ZIP container reference overlapping memory regions or when file entries contain overlapping data structures that the unzip utility cannot properly resolve. This type of flaw falls under the CWE-400 category of "Uncontrolled Resource Consumption" and represents a classic denial of service vulnerability that can be exploited through resource exhaustion attacks.
The operational impact of CVE-2019-13232 extends across multiple system environments where ZIP file processing occurs automatically or without proper input validation. Systems that process email attachments, handle file uploads from untrusted sources, or automatically extract ZIP archives for further processing become vulnerable to this attack vector. The vulnerability can be exploited in various contexts including web applications, automated file processing systems, and network services that accept ZIP file inputs. Attackers can create specially crafted ZIP files that consume excessive system resources during extraction, potentially leading to system crashes, service unavailability, or complete resource exhaustion. This makes the vulnerability particularly dangerous in environments where automated processing occurs without proper resource limits or input sanitization, as it can be used to disrupt services or cause system-wide failures.
Mitigation strategies for CVE-2019-13232 should focus on both immediate defensive measures and long-term architectural improvements. Organizations should immediately update to patched versions of Info-ZIP UnZip where available, as this represents the most direct solution to the vulnerability. Additionally, implementing proper input validation and resource limiting mechanisms can help prevent exploitation by constraining memory and processing usage during ZIP file extraction. Network security controls should include ZIP file scanning and content validation to prevent malicious archives from reaching systems that process them automatically. The ATT&CK framework categorizes this vulnerability under the "Resource Exhaustion" technique, where adversaries leverage software flaws to consume system resources and cause denial of service. Organizations should also consider implementing sandboxing techniques for ZIP file processing, establishing strict file size limits, and monitoring for unusual resource consumption patterns during file extraction operations. These defensive measures align with industry best practices for handling untrusted file formats and help prevent the exploitation of similar vulnerabilities in other archive processing utilities.