CVE-2026-124308 in vvdec
Summary
by MITRE • 11/07/2026
Fraunhofer HHI VVdeC before 3.2.1 contains a heap use-after-free vulnerability in DecLibRecon::createSubPicRefBufs because decompressPicture clears m_subPicExtTasks without waiting for pending tasks. Attackers can supply a crafted multi-subpicture VVC bitstream to decoders using two or more threads, causing heap memory corruption or a decoder crash.
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Analysis
by VulDB Data Team • 11/07/2026
The vulnerability identified in Fraunhofer HHI VVdeC versions prior to 3.2.1 represents a critical concurrency flaw within the video decoding subsystem, specifically located in the DecLibRecon::createSubPicRefBufs function. This issue is classified as a heap use-after-free condition, which falls under CWE-416 in the Common Weakness Enumeration taxonomy. The root cause stems from an improper synchronization mechanism during the decompression process. When the system executes decPicture to handle video frame reconstruction, it initiates asynchronous tasks for sub-picture processing via m_subPicExtTasks. However, the implementation fails to wait for these pending background threads to complete their execution before clearing or releasing the associated memory structures. This race condition creates a window of opportunity where allocated heap memory can be freed while still being actively accessed by concurrent worker threads that are processing different parts of the same video frame.
The operational impact of this vulnerability is significant, particularly in environments where high-performance decoding with multi-threading is utilized to accelerate video playback or streaming. An attacker who controls the input data can craft a malicious VVC (Versatile Video Coding) bitstream containing multiple sub-pictures designed to trigger specific timing conditions that exploit this race condition. By supplying such a crafted stream, an adversary forces the decoder into a state where it attempts to read from or write to memory locations that have already been deallocated by the main thread. This results in heap memory corruption, which can lead to application crashes and denial of service scenarios. In more severe cases, depending on the specific architecture and how the corrupted data is interpreted, this use-after-free condition could potentially be leveraged for arbitrary code execution, allowing an attacker to compromise the integrity and confidentiality of the host system running the vulnerable decoder.
From a threat modeling perspective, this vulnerability aligns with ATT&CK technique T1203, which covers Exploitation for Client Execution, as it targets client-side video processing software. The attack vector involves manipulating media files or streams, making it relevant to scenarios involving social engineering attacks via malicious video attachments or compromised streaming services that serve malformed content. The lack of proper thread synchronization highlights a common pitfall in high-performance multimedia applications where developers prioritize throughput over strict memory safety guarantees during concurrent operations.
Mitigation strategies must focus on both immediate patching and long-term architectural improvements. The primary remediation is to upgrade the Fraunhofer HHI VVdeC library to version 3.2.1 or later, where this synchronization issue has been addressed by ensuring that all pending sub-picture tasks are fully completed before any associated memory resources are released. For systems unable to immediately update, implementing a temporary workaround involves disabling multi-threaded decoding if the performance impact is acceptable for the specific use case, thereby eliminating the concurrency window required to trigger the vulnerability. Furthermore, developers integrating this library should enforce strict input validation and fuzzing of VVC bitstreams during development cycles to detect similar synchronization flaws early in the software lifecycle. Adopting memory-safe programming practices and utilizing static analysis tools that specialize in detecting data races can also help prevent recurrence of such concurrency-related vulnerabilities in future implementations.