CVE-2026-51990 in Input Method
Summary
by MITRE • 09/16/2026
An issue in Sogou Sogou Input Method < 16.3.0.3498 (fixed in 16.3.0.3498) allows a remote attacker to execute arbitrary code via the biz_helper.exe component
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Analysis
by VulDB Data Team • 09/16/2026
The vulnerability identified in Sogou Input Method versions prior to 16.3.0.3498 represents a critical security flaw within the application's auxiliary processing components, specifically targeting the biz_helper.exe executable. This software is widely used for Chinese language input and text prediction on Windows systems, making it a high-value target for attackers seeking persistent access or privilege escalation vectors. The core of this vulnerability lies in how the biz_helper.exe component handles data inputs from remote sources. As an auxiliary helper process, it often operates with elevated privileges to facilitate seamless integration between the main application interface and system-level input services. When processing specific malformed or specially crafted requests sent over a network connection, the component fails to adequately validate the structure and content of the incoming data. This lack of rigorous boundary checking allows an attacker to inject malicious payloads that exploit memory corruption errors, such as buffer overflow conditions, within the process address space.
From a technical perspective, this flaw aligns with Common Weakness Enumeration (CWE) categories related to improper input validation and potential out-of-bounds write operations. The absence of proper sanitization routines means that external data is treated as executable code or used to overwrite critical memory structures like return addresses or function pointers. By carefully crafting the exploit payload, a remote attacker can manipulate the control flow of biz_helper.exe during its execution cycle. This manipulation enables the arbitrary execution of shellcode or other malicious binaries loaded into the process context. Since helper processes in input method editors often run with user-level privileges but may have access to sensitive system resources or clipboard data, successful exploitation grants the attacker a foothold within the victim's environment that can be leveraged for further lateral movement or data exfiltration.
The operational impact of this vulnerability is significant due to the ubiquity and persistence mechanisms associated with input method software. Sogou Input Method typically installs as a system service or runs in the background, ensuring it remains active during user sessions. Consequently, an attacker who successfully exploits this flaw can achieve remote code execution without requiring physical access or prior authentication on the target machine. This characteristic places the vulnerability firmly within the MITRE ATT&CK framework under techniques related to Remote Code Execution and potentially Initial Access if exploited via phishing vectors that trigger the vulnerable component. The ability to execute arbitrary code means an attacker could install backdoors, keyloggers, or ransomware, compromising the confidentiality, integrity, and availability of the affected system. Furthermore, because input methods interact closely with user keystrokes, a compromised instance poses additional risks regarding credential theft through keyboard logging capabilities inherent in such software architectures.
Mitigation strategies must prioritize immediate patching to address this critical flaw. Users running versions of Sogou Input Method earlier than 16.3.0.3498 are advised to update to the latest stable release where these memory safety checks and input validation routines have been implemented by the vendor. In environments where automatic updates cannot be enforced, system administrators should manually verify version numbers across all endpoints and apply patches during maintenance windows. Additionally, implementing application whitelisting policies can restrict the execution of biz_helper.exe or other auxiliary components to only known good paths, reducing the impact if an exploit is attempted. Network segmentation and strict firewall rules limiting inbound connections to input method helper services can also mitigate the risk of remote exploitation by preventing unauthorized network traffic from reaching the vulnerable component until patches are applied.