CVE-2026-108400 in Windows
Summary
by MITRE • 10/14/2026
Integer overflow or wraparound in Microsoft Windows Codecs Library allows an unauthorized attacker to execute code over a network.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability identified within the Microsoft Windows Codecs Library represents a critical security flaw rooted in improper handling of integer arithmetic operations, specifically manifesting as an integer overflow or wraparound condition. This type of defect typically occurs when a calculation exceeds the maximum value that can be stored in a specific data type, causing it to roll over to a very small number or negative value rather than triggering an error. In the context of image processing and codec libraries, this often happens during memory allocation calculations where the size required for a buffer is computed based on user-supplied input such as image dimensions or metadata fields. If these inputs are not rigorously validated before being used in arithmetic operations, an attacker can craft maliciously formatted media files that cause the calculated buffer size to wrap around to a significantly smaller value than intended.
When this integer overflow occurs, the system allocates a memory buffer that is far too small to hold the actual data described by the malformed input. Subsequently, when the codec attempts to write or copy the full extent of the image data into this undersized buffer, a heap-based buffer overflow ensues. This overwrite operation corrupts adjacent memory structures on the heap, potentially overwriting function pointers, object headers, or other critical control data. Because the Windows Codecs Library is frequently invoked by various applications including web browsers, email clients, and document viewers to render images and media content, this vulnerability can be triggered remotely without any user interaction beyond opening a maliciously crafted file or visiting a compromised website that serves such files via standard HTTP requests.
The operational impact of this flaw is severe, as it allows an unauthorized attacker to achieve arbitrary code execution on the affected system with the privileges of the current user. By carefully crafting the heap layout and exploiting the memory corruption, an attacker can redirect program flow to execute shellcode or other malicious payloads embedded within the malformed media file. This capability effectively compromises the confidentiality, integrity, and availability of the target machine. Since modern operating systems often run applications under standard user privileges rather than administrative rights, while this may limit some system-wide changes, it still allows for significant compromise including data theft, installation of additional malware, or use as a pivot point within an internal network. The vulnerability is classified under CWE-190 Integer Overflow or Wraparound and aligns with ATT&CK techniques related to exploitation for remote code execution, specifically leveraging memory corruption vulnerabilities in application components.
Mitigation strategies primarily involve applying the latest security patches released by Microsoft that address this specific flaw in the Windows Codecs Library. Organizations should ensure their systems are updated promptly through automated patch management processes. In environments where immediate patching is not feasible, network-level controls such as deep packet inspection or web proxies can be configured to block access to untrusted sources of media files or to sanitize incoming content before it reaches client applications. Additionally, enabling application control policies and restricting the execution of unsigned code can help mitigate the impact if an exploit attempt occurs by preventing the malicious payload from executing even after memory corruption has taken place. Regular security awareness training for users regarding suspicious file attachments and links also serves as a vital layer of defense against social engineering tactics that might be used to deliver such exploits.