CVE-2022-30976 in GPAC
Summary
by MITRE • 05/18/2022
GPAC 2.0.0 misuses a certain Unicode utf8_wcslen (renamed gf_utf8_wcslen) function in utils/utf.c, resulting in a heap-based buffer over-read, as demonstrated by MP4Box.
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Analysis
by VulDB Data Team • 05/26/2022
The vulnerability identified as CVE-2022-30976 affects GPAC version 2.0.0 and represents a critical heap-based buffer over-read condition that stems from improper handling of Unicode string operations within the utility functions. This flaw specifically manifests in the utf8_wcslen function, which has been renamed to gf_utf8_wcslen in the utils/utf.c source file, creating a scenario where memory access exceeds the bounds of allocated heap buffers. The issue is particularly concerning as it impacts the MP4Box utility, which is a core component of the GPAC multimedia framework used for processing and manipulating various media formats.
The technical root cause of this vulnerability lies in the incorrect implementation of the Unicode string length calculation function that processes UTF-8 encoded strings. When the gf_utf8_wcslen function processes certain Unicode sequences, it fails to properly validate the boundaries of the input string, leading to scenarios where the function attempts to read memory locations beyond the allocated buffer space. This over-read condition occurs because the implementation does not adequately account for the variable-length nature of UTF-8 encoding, where characters can be represented using one to four bytes, and the function's boundary checking mechanisms are insufficient to prevent access to adjacent memory regions.
The operational impact of this vulnerability extends beyond simple memory corruption, as it creates potential attack vectors that could be exploited by malicious actors to execute arbitrary code or cause denial of service conditions. When MP4Box processes media files containing specially crafted Unicode sequences, the buffer over-read can lead to information disclosure, application crashes, or potentially more severe consequences depending on the execution environment. The heap-based nature of the vulnerability means that attackers could potentially manipulate heap metadata or overwrite critical program structures, making this a particularly dangerous flaw in multimedia processing software where input files are often sourced from untrusted third parties.
Security practitioners should consider this vulnerability in the context of CWE-125, which describes out-of-bounds read conditions, and potentially CWE-787, which covers out-of-bounds write vulnerabilities that can result from similar buffer handling issues. The attack surface aligns with ATT&CK techniques related to code injection and privilege escalation through software supply chain compromises, as multimedia processing applications often handle untrusted input from various sources. Organizations should prioritize updating to patched versions of GPAC, implementing input validation measures, and monitoring for exploitation attempts targeting this specific buffer over-read condition. The vulnerability demonstrates the critical importance of proper Unicode handling in security-sensitive applications and underscores the need for comprehensive testing of internationalized string processing functions in multimedia frameworks.
This flaw highlights the broader challenge of Unicode security in multimedia processing software where complex encoding schemes must be handled correctly to prevent memory safety issues. The vulnerability serves as a reminder that seemingly benign utility functions can become critical attack surfaces when they handle user-supplied data without proper boundary validation, particularly in environments where multimedia processing applications are frequently exposed to untrusted input. Proper mitigation requires not only updating to fixed versions but also implementing defensive programming practices such as bounds checking, static analysis of Unicode processing functions, and comprehensive testing of internationalized string handling in security-critical applications.