CVE-2026-77495 in Windows
Summary
by MITRE • 09/09/2026
Heap-based buffer overflow in Windows Imaging Component allows an unauthorized attacker to execute code over a network.
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability described involves a heap-based buffer overflow within the Microsoft Windows Imaging Component, a core subsystem responsible for processing various image file formats such as JPEG, PNG, and TIFF. This component is deeply integrated into the operating system's user interface layer and is frequently invoked by applications ranging from web browsers to photo viewers when rendering or manipulating visual content. The specific flaw arises during the parsing of malformed or specially crafted image files where memory allocation does not properly account for the size of incoming data structures. When an attacker provides input that exceeds the allocated buffer space on the heap, it results in adjacent memory being overwritten with arbitrary data. This corruption disrupts the internal state management of the imaging component and can lead to the execution of malicious code under the context of the currently logged-in user or service account processing the image.
From a technical perspective, this vulnerability is classified as CWE-122, which denotes heap-based buffer overflow. The exploitation mechanism typically involves crafting an image file with specific metadata or pixel data that triggers the erroneous memory write operation. By carefully controlling the contents of the overwritten memory region, an attacker can manipulate function pointers or exception handlers within the process address space. This manipulation allows for arbitrary code execution without requiring prior authentication on the target system if the vulnerability is triggered through network-accessible services such as IIS image processing modules or remote desktop session host components that automatically parse incoming images. The ability to execute code over a network significantly elevates the severity of this flaw, transforming it from a local privilege escalation risk into a potential vector for widespread worm-like propagation across vulnerable networks.
The operational impact of successfully exploiting this vulnerability is severe and multifaceted. An attacker who gains control through this heap overflow can install programs, view, change, or delete data, and create new accounts with full user rights. In enterprise environments where image processing occurs on central servers handling document management systems or web portals, a successful exploit could lead to the compromise of sensitive corporate information. Furthermore, because the Windows Imaging Component is often used in background processes that may run with elevated privileges depending on configuration, attackers might leverage this initial foothold for privilege escalation to SYSTEM level access. This would grant them complete control over the affected system, enabling persistent backdoors, lateral movement within the network, and potential disruption of critical business operations through ransomware deployment or data exfiltration.
Mitigation strategies must address both immediate remediation and long-term architectural resilience. The primary defense is the timely application of security patches released by Microsoft that correct the memory allocation logic within the Windows Imaging Component. Organizations should prioritize patching systems exposed to untrusted image sources, particularly those running web servers or file sharing services. In addition to patching, implementing strict input validation at network perimeter devices can help filter out malformed requests before they reach vulnerable components. Security teams should also enforce least privilege principles for services that utilize the imaging component, ensuring that even if exploitation occurs, the resulting code execution is limited in scope and impact. Regular vulnerability scanning focused on image processing libraries and monitoring for anomalous memory behavior or unexpected process spawns can provide early detection indicators of attempted exploits targeting this specific weakness aligned with MITRE ATT&CK techniques related to initial access via spearphishing attachment or drive-by compromise.