CVE-2020-9385 in Zint
Summary
by MITRE
A NULL Pointer Dereference exists in libzint in Zint 2.7.1 because multiple + characters are mishandled in add_on in upcean.c, when called from eanx in upcean.c during EAN barcode generation.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 04/02/2024
The vulnerability CVE-2020-9385 represents a critical NULL pointer dereference issue within the libzint library version 2.7.1, specifically affecting EAN barcode generation functionality. This flaw manifests when the library processes barcode data containing multiple consecutive plus characters, creating a scenario where memory access violations can occur during the barcode rendering process. The vulnerability is rooted in the improper handling of input data within the add_on function located in the upcean.c source file, which subsequently calls the eanx function that triggers the problematic code path. The issue demonstrates a classic software security weakness that can potentially lead to application crashes or, in more severe scenarios, arbitrary code execution depending on the system's memory management and error handling mechanisms.
The technical implementation of this vulnerability stems from inadequate input validation and error checking within the barcode generation pipeline. When multiple consecutive plus characters are encountered during EAN barcode processing, the add_on function fails to properly validate the input data structure, leading to a situation where a NULL pointer reference occurs during the subsequent processing steps. This condition typically arises from the library's inability to handle edge cases in the input data format, particularly when dealing with special character sequences that are not properly sanitized or validated before being processed through the barcode generation algorithms. The flaw specifically affects the upcean.c module where the EAN barcode generation logic resides, making it particularly concerning for applications that rely on this library for barcode creation and processing.
The operational impact of CVE-2020-9385 extends beyond simple application instability, potentially creating denial of service conditions that can disrupt barcode generation services across numerous software applications. Systems utilizing libzint for EAN barcode creation, including inventory management systems, retail point-of-sale solutions, and various document processing applications, become vulnerable to crashes when encountering malformed input data containing multiple plus characters. This vulnerability aligns with CWE-476 which describes NULL pointer dereference conditions, and represents a significant concern for software supply chains where the libzint library is integrated. The attack surface is particularly broad as EAN barcodes are widely used across different industries, making this vulnerability potentially exploitable in multiple contexts where barcode generation is performed automatically or through user input.
Mitigation strategies for CVE-2020-9385 should focus on immediate library updates to versions that address the NULL pointer dereference issue, as the vendor has released patches to resolve this vulnerability. Organizations should implement input validation measures to sanitize barcode data before processing, particularly when handling user-provided input that might contain special character sequences. The remediation process involves upgrading to libzint version 2.7.2 or later, which includes proper error handling for the specific case of multiple plus characters in EAN barcode generation. Additionally, system administrators should conduct comprehensive vulnerability assessments to identify all applications that depend on libzint, ensuring that proper patch management procedures are implemented across the entire infrastructure. Security monitoring should be enhanced to detect potential exploitation attempts targeting this vulnerability, particularly in systems where barcode generation is automated or integrated into critical business processes. The ATT&CK framework categorizes this vulnerability under defense evasion and execution tactics, as it can be leveraged to disrupt services or potentially escalate privileges if the affected applications have elevated system permissions.