CVE-2026-38344 in FFmpeg
Summary
by MITRE • 08/28/2026
A NULL pointer dereference in the get_min_buffer_size function (/libswscale/slice.c) of FFmpeg N-122528-gdd2976b9e1 allows attackers to cause a Denial of Service (DoS) via supplying a crafted video file.
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Analysis
by VulDB Data Team • 08/28/2026
The vulnerability identified in the specified version of FFmpeg, specifically within the get_min_buffer_size function located at /libswscale/slice.c, represents a critical memory safety issue classified as a NULL pointer dereference. This flaw arises when the software fails to properly validate input parameters before attempting to access or manipulate memory addresses associated with video processing buffers. In the context of multimedia frameworks like FFmpeg, which are designed to handle complex and often untrusted media files, such validation failures can lead to catastrophic application crashes. The specific function involved is responsible for determining the minimum buffer size required for slice-based image scaling operations. When a crafted video file containing malformed or unexpected metadata triggers this code path without proper checks, the program attempts to dereference a pointer that holds no valid memory address, resulting in an immediate segmentation fault and termination of the process.
From a technical perspective, this vulnerability falls under the Common Weakness Enumeration category CWE-476, which defines NULL Pointer Dereference as a condition where software incorrectly performs a null pointer de-reference, leading to crashes or other unintended behaviors. The operational impact is primarily focused on Denial of Service (DoS), as attackers can exploit this flaw by delivering specially crafted video files through various vectors such as email attachments, web uploads, or direct file access. Upon processing the malicious input, the application will crash, disrupting service availability for legitimate users who rely on the media conversion or playback capabilities provided by FFmpeg-based applications. This type of attack does not typically allow for remote code execution in this specific instance but significantly degrades system reliability and can be used to exhaust server resources if automated systems repeatedly attempt to process malicious inputs without proper error handling at higher levels.
The exploitation mechanism relies on the attacker's ability to construct a video file that triggers the vulnerable code path within the slice processing logic. By manipulating header information or frame data structures, an adversary can force the get_min_buffer_size function to encounter conditions where expected pointers are uninitialized or explicitly set to null due to prior allocation failures or logical errors in the parsing routine. This aligns with tactics observed in advanced persistent threats and automated scanning tools that target multimedia libraries for instability-based attacks. The ATT&CK framework categorizes such behavior under techniques related to resource exhaustion, specifically T1499 Endpoint Denial of Service, where the goal is to make a specific target unavailable by overwhelming it or causing crashes through malformed inputs rather than consuming computational resources in a sustained manner.
Mitigation strategies for this vulnerability involve both immediate patching and long-term defensive coding practices. The primary remediation step is to update FFmpeg to a version that includes the fix for this NULL pointer dereference, ensuring that the get_min_buffer_size function properly validates all pointers before use. Developers should implement rigorous input validation checks within multimedia processing libraries to ensure that memory allocations succeed before proceeding with operations dependent on those buffers. Additionally, deploying runtime protection mechanisms such as Address Sanitizers during development and testing phases can help identify similar issues early in the software lifecycle. For end-users and administrators, restricting the upload of untrusted media files or implementing sandboxing for video processing services can reduce the attack surface. It is also advisable to configure application watchdogs that automatically restart crashed processes, thereby maintaining service availability even if individual instances are compromised by such denial-of-service attempts.