CVE-2018-6358 in libming
Summary
by MITRE
The printDefineFont2 function (util/listfdb.c) in libming through 0.4.8 is vulnerable to a heap-based buffer overflow, which may allow attackers to cause a denial of service or unspecified other impact via a crafted FDB file.
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Analysis
by VulDB Data Team • 02/02/2023
The vulnerability identified as CVE-2018-6358 affects the libming library version 0.4.8 and earlier, specifically within the printDefineFont2 function located in util/listfdb.c. This library serves as a SWF (Small Web Format) file manipulation tool that processes Flash-based file formats, making it a critical component in multimedia content handling across various applications and systems. The flaw manifests as a heap-based buffer overflow that occurs when processing malformed FDB (Flash Database) files, which are used to store font information within SWF files and related multimedia formats.
The technical implementation of this vulnerability stems from inadequate input validation within the printDefineFont2 function, which fails to properly bounds-check data when parsing font definitions from FDB files. When an attacker crafts a malicious FDB file containing oversized or malformed font data, the function attempts to write beyond the allocated heap memory buffer, leading to memory corruption. This heap overflow condition can result in unpredictable program behavior, application crashes, or potentially more severe consequences depending on the execution environment and memory layout. The vulnerability is particularly concerning because it operates within a library that is widely used for processing multimedia content, making it an attractive target for exploitation.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as the heap corruption could potentially be leveraged for more sophisticated attacks depending on the target system configuration and memory protection mechanisms in place. Systems that rely on libming for processing untrusted SWF or FDB content are at risk, including web applications, content management systems, and multimedia processing pipelines. The vulnerability affects any application that utilizes the affected library and processes potentially malicious FDB files, creating a broad attack surface that could impact numerous end-user systems and server environments.
Mitigation strategies for CVE-2018-6358 should prioritize immediate patching of the libming library to version 0.4.9 or later, which contains the necessary fixes for the buffer overflow vulnerability. Organizations should implement strict input validation measures when processing FDB files, including file format verification and size limitation checks to prevent exploitation attempts. Network segmentation and access controls can help limit the potential impact of successful exploitation attempts, while application-level sandboxing may provide additional protection layers. From a cybersecurity perspective, this vulnerability aligns with CWE-121 Heap-based Buffer Overflow and represents a typical example of how legacy multimedia libraries can contain critical security flaws that persist across multiple versions. The ATT&CK framework categorizes this as a memory corruption technique that could potentially lead to privilege escalation or arbitrary code execution depending on the exploitation context and target environment configuration.