CVE-2016-9636 in GStreamer
Summary
by MITRE
Heap-based buffer overflow in the flx_decode_delta_fli function in gst/flx/gstflxdec.c in the FLIC decoder in GStreamer before 1.10.2 allows remote attackers to execute arbitrary code or cause a denial of service (application crash) by providing a 'write count' that goes beyond the initialized buffer.
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Analysis
by VulDB Data Team • 05/15/2026
The CVE-2016-9636 vulnerability represents a critical heap-based buffer overflow within the GStreamer multimedia framework's FLIC decoder component. This flaw exists in the flx_decode_delta_fli function located in gst/flx/gstflxdec.c, affecting all GStreamer versions prior to 1.10.2. The vulnerability manifests when processing FLIC (FLI/FLC) animation files, which are legacy animation formats commonly used in older multimedia applications and games. The issue arises from inadequate bounds checking during the decoding process where the application fails to validate the 'write count' parameter against the actual buffer boundaries, creating a predictable memory corruption scenario.
The technical implementation of this vulnerability stems from the FLIC decoder's handling of delta frames within animation sequences. When the decoder encounters a delta frame, it attempts to write data to a pre-allocated buffer based on a 'write count' value specified in the file header. However, the implementation does not properly validate whether this write count exceeds the allocated buffer size, allowing attackers to craft malicious FLIC files that trigger buffer overflows. This heap-based overflow occurs because the decoder allocates memory based on initial assumptions about the data size, but subsequent writes extend beyond these boundaries into adjacent memory regions. The vulnerability falls under CWE-121, Heap-based Buffer Overflow, and specifically demonstrates poor input validation and memory management practices that are fundamental to secure coding standards.
The operational impact of CVE-2016-9636 extends beyond simple denial of service to potential remote code execution capabilities. Attackers can exploit this vulnerability by delivering malicious FLIC files through various attack vectors including web downloads, email attachments, or file sharing platforms. When a vulnerable application processes these crafted files, the buffer overflow can corrupt adjacent memory, potentially overwriting function pointers, return addresses, or other critical program state information. This memory corruption can lead to arbitrary code execution with the privileges of the affected application, or alternatively cause application crashes and system instability. The vulnerability is particularly concerning in web browsers and media players that automatically process FLIC content, as these represent common attack surfaces for remote exploitation. According to ATT&CK framework, this vulnerability maps to T1203 - Exploitation for Client Execution and T1059 - Command and Scripting Interpreter, as it enables remote code execution through media file processing.
Mitigation strategies for CVE-2016-9636 primarily focus on immediate version upgrades to GStreamer 1.10.2 or later, which contain the necessary patches to address the buffer overflow issue. Organizations should implement comprehensive patch management procedures to ensure all affected systems receive updates promptly, particularly in environments where media processing applications are prevalent. Additional protective measures include implementing content filtering mechanisms that scan and validate media files before processing, deploying sandboxing techniques for media applications, and configuring applications to limit memory allocation for media processing components. Network-based mitigations such as web application firewalls and content inspection systems can help prevent the delivery of malicious FLIC files to vulnerable systems. Security monitoring should focus on detecting unusual application behavior, memory corruption patterns, and potential exploitation attempts through media file processing. The vulnerability also underscores the importance of input validation and bounds checking in multimedia codecs, as similar issues may exist in other legacy format decoders within the GStreamer framework and similar multimedia libraries.