CVE-2017-13135 in x265
Summary
by MITRE
A NULL Pointer Dereference exists in VideoLAN x265, as used in libbpg 0.9.7 and other products, because the CUData::initialize function in common/cudata.cpp mishandles memory-allocation failure.
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Analysis
by VulDB Data Team • 01/24/2021
The vulnerability identified as CVE-2017-13135 represents a critical null pointer dereference flaw within the VideoLAN x265 video encoding library that affects libbpg 0.9.7 and numerous other software implementations. This issue stems from improper error handling during memory allocation processes within the CUData::initialize function located in the common/cudata.cpp source file. The flaw demonstrates characteristics consistent with CWE-476, which specifically addresses null pointer dereference conditions that can lead to application crashes or potential exploitation scenarios. The vulnerability manifests when the system encounters a memory allocation failure during the initialization phase of video compression units, creating a scenario where the application attempts to access a null pointer reference.
The technical implementation of this vulnerability occurs during the video encoding process when the CUData::initialize function fails to properly validate memory allocation results before proceeding with subsequent operations. When memory allocation fails, the function should gracefully handle the error condition by either returning an appropriate error code or terminating the operation safely. However, in this case, the code path continues execution without proper null checking, leading to a situation where a null pointer is dereferenced during the video processing pipeline. This behavior creates an exploitable condition that can result in denial of service attacks or potentially allow for more sophisticated exploitation techniques depending on the target environment. The flaw is particularly concerning because it occurs in a core video processing component that is widely integrated across various multimedia applications and systems.
The operational impact of CVE-2017-13135 extends beyond simple application crashes, as it represents a fundamental weakness in the memory management and error handling protocols of the affected software components. Systems utilizing vulnerable versions of libbpg or other products incorporating the x265 library could experience unexpected termination of video processing operations, leading to service disruption and potential data loss during critical encoding tasks. From an attack perspective, this vulnerability aligns with ATT&CK technique T1499.004, which involves network denial of service through resource exhaustion or manipulation of critical system components. The vulnerability affects not only individual applications but also entire software ecosystems that depend on x265 for video compression, creating a widespread impact across multimedia platforms, content delivery networks, and video processing infrastructure.
Mitigation strategies for this vulnerability require immediate patching of affected software components to address the null pointer dereference issue in the CUData::initialize function. Security teams should prioritize updating libbpg to version 0.9.8 or later, which includes the necessary memory allocation error handling improvements. Additionally, implementing proper input validation and memory allocation failure checks within the application code can provide defensive measures against similar issues. Organizations should consider deploying runtime protections such as address space layout randomization and stack canaries to limit the potential impact of exploitation attempts. The fix implemented in the patched versions demonstrates proper error handling by ensuring that memory allocation failures are appropriately detected and managed before any subsequent pointer operations are attempted, thereby preventing the null pointer dereference condition from occurring.