CVE-2016-9635 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 'skip count' that goes beyond initialized buffer.
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Analysis
by VulDB Data Team • 05/15/2026
The CVE-2016-9635 vulnerability represents a critical heap-based buffer overflow affecting the GStreamer multimedia framework's FLIC decoder component. This vulnerability exists within the flx_decode_delta_fli function located in gst/flx/gstflxdec.c, specifically impacting GStreamer versions prior to 1.10.2. The flaw manifests when processing FLIC (FLI/FLC) animation files, which are legacy animation formats commonly used in older multimedia applications and games. The vulnerability stems from insufficient bounds checking when handling the 'skip count' parameter within the delta frame decoding process, creating a condition where attacker-controlled data can overwrite adjacent heap memory regions.
The technical implementation of this vulnerability involves the FLIC decoder's handling of delta frames, where the 'skip count' field determines how many pixels to skip during frame decoding operations. When this value exceeds the bounds of the pre-allocated buffer, the decoder performs an out-of-bounds write operation that corrupts heap metadata and potentially allows arbitrary code execution. The heap corruption occurs because the function does not validate that the skip count parameter remains within the initialized buffer boundaries before performing memory operations. This type of vulnerability falls under CWE-121 heap-based buffer overflow, which is classified as a memory safety issue that can lead to both privilege escalation and denial of service conditions. The vulnerability is particularly dangerous because it can be triggered through remote file processing, making it suitable for exploitation in web-based or networked environments where GStreamer is used to decode multimedia content.
From an operational impact perspective, this vulnerability presents significant risks to systems that utilize GStreamer for multimedia processing, particularly those exposed to untrusted content such as web browsers, media players, or content delivery systems. The remote exploitation capability means that attackers can craft malicious FLIC files that, when processed by vulnerable applications, will trigger the buffer overflow and potentially execute arbitrary code with the privileges of the affected process. This could lead to complete system compromise, especially when the vulnerable applications run with elevated privileges. The vulnerability also enables denial of service attacks that can crash applications and render them unavailable to legitimate users. The ATT&CK framework categorizes this as a code injection technique under T1059, specifically targeting heap-based buffer overflow vulnerabilities as a means to achieve remote code execution.
Mitigation strategies for CVE-2016-9635 primarily involve upgrading to GStreamer version 1.10.2 or later, where the vulnerability has been addressed through proper bounds checking and input validation. System administrators should implement immediate patch management procedures to ensure all affected systems receive the necessary updates. Additionally, organizations should consider implementing input validation controls at the application level, particularly for multimedia file processing components, to reduce the attack surface. Network-based mitigations could include content filtering to block FLIC files from untrusted sources, while application-level sandboxing can limit the potential impact if exploitation occurs. Security monitoring should focus on detecting unusual memory access patterns and heap corruption indicators that might signal exploitation attempts. The vulnerability serves as a reminder of the importance of input validation in multimedia processing libraries and the critical need for regular security updates in open-source multimedia frameworks.