CVE-2026-124309 in vvdec
Summary
by MITRE • 11/07/2026
Fraunhofer HHI VVdeC before 3.2.1 contains a heap out-of-bounds read vulnerability in SEIReader::xParseSEIScalableNesting that allows attackers to read past heap allocations by casting the SEI wrapper object instead of its payload. Attackers can supply a crafted VVC bitstream with a scalable nesting SEI containing a nested buffering period SEI to crash the decoder or copy adjacent heap memory.
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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 security flaw within the video coding standard implementation, specifically affecting the handling of Supplemental Enhancement Information (SEI) messages. This library is widely used for decoding Versatile Video Coding streams and serves as a foundational component in many multimedia applications. The specific defect resides in the SEIReader::xParseSEIScalableNesting function, which is responsible for parsing scalable nesting SEI units within the video bitstream. During this process, the software fails to correctly distinguish between the metadata wrapper of an SEI message and its actual payload data. This logical error leads to a heap-based out-of-bounds read condition when processing malformed input files crafted by an attacker.
From a technical perspective, the root cause is rooted in improper memory access controls during the parsing phase. When the decoder encounters a scalable nesting SEI that contains a nested buffering period SEI, it incorrectly casts the entire SEI wrapper object rather than isolating and accessing only its payload content. This misalignment causes the parser to read data from memory locations immediately following the allocated buffer for the SEI structure. Because this operation occurs on the heap, an attacker can manipulate the bitstream to control what adjacent memory contents are exposed or trigger a segmentation fault by reading invalid addresses. The vulnerability allows for arbitrary information disclosure if the process does not crash, potentially leaking sensitive data stored in neighboring heap allocations such as cryptographic keys or user credentials.
The operational impact of this flaw is significant due to its potential for both denial-of-service and unauthorized data access. If an attacker supplies a specially crafted VVC bitstream containing the malformed scalable nesting SEI structure, they can cause the decoder application to crash by triggering an out-of-bounds read that accesses unmapped or protected memory pages. This results in a reliable denial of service against any system relying on this library for video processing. Furthermore, if the execution environment allows for information leakage without immediate termination, the vulnerability enables remote attackers to copy adjacent heap memory contents. This capability can be leveraged as part of a larger attack chain to bypass security mitigations or extract sensitive state information from the application process.
This issue aligns with Common Weakness Enumeration CWE-125, which describes out-of-bounds read vulnerabilities where software reads data past the end or before the beginning of the intended buffer. In terms of offensive cybersecurity frameworks, this vulnerability maps to ATT&CK technique T1083, specifically related to file and directory discovery through memory inspection techniques that exploit parsing flaws in media files. The exploitation vector is classified as remote with low complexity, requiring only a single crafted input file rather than complex interaction or authentication prerequisites if the decoder processes untrusted streams automatically.
To mitigate this risk, organizations utilizing Fraunhofer HHI VVdeC must immediately upgrade to version 3.2.1 or later where the parsing logic has been corrected to properly isolate SEI payloads from their wrappers. Input validation mechanisms should be implemented at the application layer to detect and reject malformed bitstreams before they reach the vulnerable decoder components. Additionally, developers should employ memory-safe programming practices and utilize static analysis tools configured to detect out-of-bounds access patterns in C++ codebases handling multimedia data streams. Regular security audits of third-party media libraries are essential to prevent similar parsing vulnerabilities from impacting production environments.