CVE-2017-14795 in libbpg
Summary
by MITRE
The hevc_write_frame function in libbpg.c in libbpg 0.9.7 allows remote attackers to cause a denial of service (out-of-bounds read and application crash) or possibly have unspecified other impact via a crafted BPG file, related to improper interaction with hls_pcm_sample in hevc.c in libavcodec in FFmpeg and put_pcm_var in hevcdsp_template.c in libavcodec in FFmpeg.
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Analysis
by VulDB Data Team • 11/20/2019
The vulnerability identified as CVE-2017-14795 represents a critical security flaw within the libbpg library version 0.9.7, specifically within the hevc_write_frame function that processes BPG image files. This issue stems from improper handling of data structures during the decoding process, creating a pathway for remote attackers to exploit the system through carefully crafted malicious BPG files. The vulnerability demonstrates a classic out-of-bounds read condition that can lead to application crashes and potential denial of service scenarios, making it particularly dangerous in environments where automated processing of user-supplied content occurs.
The technical root cause of this vulnerability lies in the improper interaction between multiple components within the FFmpeg library ecosystem, specifically involving the hls_pcm_sample function in hevc.c and the put_pcm_var function in hevcdsp_template.c. When a malicious BPG file is processed, the hevc_write_frame function fails to properly validate input parameters before accessing memory locations, leading to unauthorized memory access patterns. This flaw operates at the intersection of multiple codecs and decoding components, creating a complex attack surface where input validation failures in one module cascade into critical execution errors in another. The vulnerability manifests as an out-of-bounds read operation that can trigger application termination or potentially lead to more severe consequences depending on the execution context and memory layout.
From an operational impact perspective, this vulnerability poses significant risks to systems that process or serve BPG image files, particularly web applications, content management systems, and media processing services. The remote exploitation capability means that attackers can trigger the vulnerability without requiring local access or user interaction, making it particularly dangerous in publicly accessible environments. The potential for unspecified other impacts suggests that beyond simple denial of service, this vulnerability could potentially enable further exploitation vectors, including information disclosure or privilege escalation depending on the system configuration and execution environment. The vulnerability affects not just individual applications but entire ecosystems that rely on FFmpeg's codec handling capabilities for video and image processing.
Mitigation strategies for CVE-2017-14795 should prioritize immediate patching of affected libbpg versions to 0.9.8 or later, where the vulnerability has been addressed through proper input validation and bounds checking mechanisms. System administrators should implement strict file validation procedures, including MIME type checking and file format verification, before processing any BPG content. Network-level protections such as content filtering and sandboxing mechanisms should be deployed to isolate vulnerable applications from potentially malicious inputs. Additionally, monitoring and logging should be enhanced to detect unusual patterns of BPG file processing that might indicate exploitation attempts. The vulnerability aligns with CWE-125 out-of-bounds read and CWE-20 improper input validation categories, and represents a potential entry point for ATT&CK techniques involving execution through file processing and privilege escalation through application crashes. Organizations should also consider implementing automated vulnerability scanning and regular security assessments to identify similar issues in their broader software supply chain dependencies.