CVE-2021-29338 in OpenJPEG
Summary
by MITRE • 04/14/2021
Integer Overflow in OpenJPEG v2.4.0 allows remote attackers to crash the application, causing a Denial of Service (DoS). This occurs when the attacker uses the command line option "-ImgDir" on a directory that contains 1048576 files.
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Analysis
by VulDB Data Team • 11/04/2025
The vulnerability CVE-2021-29338 represents a critical integer overflow flaw in the OpenJPEG library version 2.4.0 that fundamentally compromises the stability and availability of applications relying on this component. This issue manifests when the command line utility processes a directory containing exactly 1048576 files through the "-ImgDir" option, creating a scenario where integer arithmetic exceeds the maximum representable value for the data type used in the processing loop. The flaw stems from inadequate input validation and boundary checking within the file enumeration and processing logic of the JPEG 2000 image handling library. The integer overflow occurs during the calculation or iteration process when counting files in the specified directory, where the counter variable overflows from its maximum positive value back to negative territory, causing unpredictable behavior in the application's memory management and control flow. This vulnerability directly maps to CWE-190, Integer Overflow or Wraparound, which is classified under the weakness category of integer-related issues in software security. The attack vector requires remote exploitation through command line invocation, making it particularly dangerous as it can be triggered by unauthenticated users who have access to the affected system or application interface.
The operational impact of this vulnerability extends beyond simple application crash, creating a potential denial of service condition that can render systems unavailable to legitimate users and potentially allowing attackers to disrupt critical services. When the integer overflow occurs during file processing, it typically results in segmentation faults, memory corruption, or infinite loops that cause the application to terminate unexpectedly or enter an unrecoverable state. The specific file count of 1048576 represents a mathematical boundary condition that triggers the overflow in the underlying integer arithmetic, making this vulnerability particularly predictable and exploitable. The affected OpenJPEG library is widely used in various applications including medical imaging systems, digital archiving platforms, and content management systems that handle JPEG 2000 formatted images. The DoS condition affects not only the immediate application but can also impact the broader system stability, especially when the vulnerable component is part of larger software ecosystems or network services. This vulnerability aligns with ATT&CK technique T1499.004, Network Denial of Service, as it can be leveraged to create availability issues that disrupt normal operations.
Mitigation strategies for CVE-2021-29338 require immediate patching of the OpenJPEG library to version 2.4.1 or later, which contains the necessary fixes for the integer overflow condition. Organizations should implement robust input validation measures that limit directory file counts or implement proper boundary checking before processing large directory structures. The recommended approach includes deploying application-level restrictions that prevent the processing of directories exceeding predefined file thresholds, typically well below the overflow boundary. System administrators should also consider implementing monitoring and alerting mechanisms to detect unusual file processing patterns that might indicate exploitation attempts. Additionally, the principle of least privilege should be enforced to limit the execution scope of vulnerable applications, reducing the potential impact of successful exploitation. Security teams should conduct comprehensive vulnerability assessments to identify all systems using affected OpenJPEG versions and ensure proper patch management protocols are in place. The fix addresses the root cause by implementing proper integer overflow checks and boundary validation, preventing the arithmetic overflow condition from occurring during file enumeration processes. Organizations should also consider implementing automated patch deployment mechanisms and regular security audits to prevent similar vulnerabilities from emerging in other components of their software supply chain.