CVE-2019-14296 in UPX
Summary
by MITRE
canUnpack in p_vmlinx.cpp in UPX 3.95 allows remote attackers to cause a denial of service (SEGV or buffer overflow, and application crash) or possibly have unspecified other impact via a crafted UPX packed file.
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Analysis
by VulDB Data Team • 04/11/2025
The vulnerability identified as CVE-2019-14296 resides within the UPX (Ultimate Packer for eXecutables) 3.95 compression utility, specifically in the p_vmlinx.cpp component that handles the unpacking process for Linux virtual machine executables. This flaw manifests in the canUnpack function which serves as a critical validation mechanism during the unpacking procedure of packed executables. The vulnerability represents a classic buffer overflow condition that can be triggered through maliciously crafted UPX packed files, potentially leading to system instability and denial of service conditions. The flaw affects the core unpacking functionality of UPX, making it a significant concern for systems that rely on UPX for executable compression and distribution.
The technical implementation of this vulnerability stems from inadequate input validation within the canUnpack function in p_vmlinx.cpp. When UPX processes a packed file, it performs various checks to determine if the file can be safely unpacked, but the validation logic fails to properly handle malformed or specially crafted input data. This insufficient boundary checking allows attackers to construct UPX packed files that contain malicious data structures which, when processed by the canUnpack function, cause memory corruption. The vulnerability can manifest as either a segmentation fault (SEGV) or buffer overflow condition, both of which result in application crashes and can be exploited remotely by attackers who have access to the target system or can influence the execution of packed files. The underlying weakness aligns with CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow scenarios.
The operational impact of CVE-2019-14296 extends beyond simple denial of service conditions to potentially enable more sophisticated attack vectors. Remote attackers who can influence the execution of UPX packed executables can trigger system crashes that may lead to availability disruption for critical services. In environments where UPX is used for software distribution or system deployment, this vulnerability could be exploited to compromise system integrity and availability. The vulnerability's remote exploitability means that attackers do not need local system access to cause harm, making it particularly dangerous in networked environments. Additionally, the unspecified other impacts mentioned in the vulnerability description suggest potential for more severe consequences including privilege escalation or information disclosure, though these remain unconfirmed. This vulnerability directly relates to ATT&CK technique T1059.007 for execution through virtualization and container environments, as it affects the integrity of executable unpacking processes in virtualized contexts.
Mitigation strategies for CVE-2019-14296 should focus on immediate patching of UPX installations to version 3.96 or later, which contains the necessary fixes for the buffer overflow conditions. Organizations should implement strict file validation procedures for any UPX packed executables that are processed within their environments, including scanning for potentially malicious content before unpacking. Network segmentation and access controls should be enforced to limit the attack surface, particularly for systems that process untrusted executable content. Regular security audits should be conducted to identify systems running vulnerable versions of UPX, and automated patch management systems should be configured to ensure timely updates. Additionally, monitoring for abnormal application crashes or segmentation faults related to UPX operations should be implemented as part of incident response protocols. The vulnerability highlights the importance of proper input validation and boundary checking in security-critical code, serving as a reminder of the potential consequences of inadequate memory management practices in compression utilities that handle untrusted data.