CVE-2017-12922 in libfpx
Summary
by MITRE
wchar.c in libfpx 1.3.1_p6 allows remote attackers to cause a denial of service (NULL pointer dereference) via a crafted fpx image.
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Analysis
by VulDB Data Team • 11/10/2019
The vulnerability identified as CVE-2017-12922 resides within the libfpx library version 1.3.1_p6, specifically in the wchar.c component which handles wide character processing for fpx image files. This flaw represents a classic null pointer dereference issue that can be exploited by remote attackers to disrupt service availability. The vulnerability manifests when the library processes maliciously crafted fpx image files that contain malformed wide character data structures, leading to a program crash when attempting to access a null pointer during the image parsing process.
The technical implementation of this vulnerability stems from inadequate input validation within the wchar.c module where the library fails to properly validate the bounds and integrity of wide character data within fpx image files. When a crafted fpx file contains unexpected or malformed wide character sequences, the parsing logic in wchar.c attempts to dereference a null pointer that should have been initialized or validated. This type of error falls under the CWE-476 category of NULL Pointer Dereference, which is a well-documented weakness in software security practices. The flaw is particularly concerning because it allows remote exploitation without requiring authentication or specialized privileges, making it an attractive target for denial of service attacks.
The operational impact of this vulnerability extends beyond simple service disruption as it can be leveraged by attackers to create persistent availability issues for systems processing fpx images. Any application or service that utilizes libfpx for image handling, including web applications, content management systems, or image processing pipelines, becomes vulnerable to this attack vector. The vulnerability can be exploited through various attack surfaces such as file upload functionalities, image processing APIs, or automated image analysis systems that accept fpx format inputs. This creates a significant risk for organizations that rely on third-party image processing libraries, particularly those in environments where continuous service availability is critical for business operations.
Mitigation strategies for CVE-2017-12922 should focus on immediate patching of the libfpx library to version 1.3.2 or later where the null pointer dereference has been addressed. System administrators should implement input validation measures that filter or reject suspicious fpx image files before they reach the libfpx processing layer. Network-based mitigations can include implementing file type validation at ingress points, using sandboxed processing environments for image files, and deploying intrusion detection systems that monitor for exploitation attempts. Organizations should also consider implementing application-level controls such as resource limits on image processing operations and implementing proper error handling that prevents crashes from propagating through system components. The vulnerability aligns with ATT&CK technique T1499.004 for network denial of service attacks, and organizations should monitor for indicators of compromise related to malformed fpx file processing activities. Additionally, regular security assessments of third-party libraries and maintaining up-to-date dependency management practices can help prevent similar vulnerabilities from being introduced into production environments.