CVE-2021-47775 in YouTube Video Grabber
Summary
by MITRE • 01/15/2026
YouTube Video Grabber, now referred to as YouTube Downloader, 1.9.9.1 contains a buffer overflow vulnerability that allows attackers to execute arbitrary code by overwriting the Structured Exception Handler. Attackers can craft a malicious payload of 712 bytes with SEH manipulation to trigger a bind shell connection on a specified local port.
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Analysis
by VulDB Data Team • 01/15/2026
The vulnerability identified as CVE-2021-47775 affects YouTube Video Grabber, also known as YouTube Downloader version 1.9.9.1, presenting a critical buffer overflow condition that fundamentally compromises system security. This flaw resides within the application's handling of structured exception handlers, creating a pathway for attackers to execute arbitrary code through deliberate manipulation of the exception handling mechanism. The vulnerability demonstrates a sophisticated attack vector that leverages the Windows structured exception handling (SEH) mechanism to gain unauthorized access to target systems.
The technical implementation of this vulnerability involves a carefully crafted malicious payload of exactly 712 bytes designed to exploit the buffer overflow condition. This payload specifically targets the structured exception handler by overwriting its memory location, effectively redirecting program execution flow to attacker-controlled code. The SEH manipulation technique represents a well-established exploitation method that has been documented in various security research publications and forms part of the attack patterns catalogued under the attack technique T1059.007 for command and script injection within the MITRE ATT&CK framework. The vulnerability specifically aligns with CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow scenarios, though the implementation here focuses on structured exception handling manipulation.
The operational impact of this vulnerability extends beyond simple code execution, as it enables attackers to establish persistent bind shell connections on specified local ports, providing remote access to compromised systems. This capability transforms a simple buffer overflow into a full system compromise scenario where attackers can maintain long-term access to vulnerable systems. The attack requires minimal privileges to execute successfully, making it particularly dangerous in environments where users may inadvertently download and execute malicious content through the vulnerable application. The 712-byte payload size suggests a precise exploitation technique that maximizes the effectiveness of the buffer overflow while minimizing the attack surface, demonstrating advanced exploitation knowledge.
Mitigation strategies for CVE-2021-47775 should prioritize immediate application updates to versions that address the buffer overflow condition and SEH manipulation vulnerability. System administrators should implement network segmentation and access controls to limit exposure of vulnerable systems, particularly those running the affected software version. The implementation of application whitelisting policies can prevent unauthorized execution of malicious payloads, while regular security audits should verify that no systems remain vulnerable to this specific exploitation technique. Additionally, network monitoring should be enhanced to detect unusual bind shell connections that may indicate exploitation attempts, as these connections represent a clear indicator of successful exploitation. Organizations should also consider implementing exploit prevention mechanisms such as data execution prevention (DEP) and address space layout randomization (ASLR) to make exploitation more difficult. The vulnerability's classification as a critical security issue necessitates immediate remediation efforts, as the combination of buffer overflow and SEH manipulation creates a high-risk scenario for system compromise and unauthorized access.