CVE-2026-85842 in Windows
Summary
by MITRE • 10/14/2026
Use of externally-controlled format string in Windows Image Acquisition allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability identified as CVE-2024-35267 represents a critical security flaw within the Windows Image Acquisition (WIA) service, specifically involving improper handling of user-supplied input that leads to a format string error. This issue arises when an authorized attacker can supply specially crafted data containing format specifiers such as %s or %x into functions that process these inputs without proper sanitization. In C and C++ programming languages, which underpin much of the Windows operating system infrastructure, format strings are used to define how subsequent arguments should be interpreted during output operations like printf-style functions. When an application fails to validate external input before passing it as a format string argument, it allows for arbitrary memory reads or writes, depending on the specific implementation details and execution context. This class of vulnerability is formally categorized under CWE-134: Use of Externally-Controlled Format String in industry-standard classification systems, highlighting the severity of allowing untrusted data to dictate program behavior at a low level.
The operational impact of this flaw is significant because it facilitates local privilege escalation on affected Windows systems. Although the vulnerability requires an attacker to have authorized access initially, typically through valid user credentials or via social engineering tactics that compromise such accounts, the ability to exploit the format string weakness allows for control over the instruction pointer and memory contents. By carefully crafting the payload, a malicious actor can overwrite critical data structures within the WIA service process space, potentially gaining execution of arbitrary code with higher privileges than those originally held by the compromised account. This effectively bypasses standard access controls and security boundaries established by the operating system's integrity levels and mandatory access control mechanisms. The presence of this vulnerability in Windows Image Acquisition is particularly concerning given that WIA is a legacy component used for interfacing with imaging devices such as scanners and digital cameras, meaning it may remain enabled on systems where peripheral hardware interaction is required or has been historically utilized.
From an offensive security perspective, this vulnerability aligns closely with techniques documented in the MITRE ATT&CK framework, specifically relating to privilege escalation via local exploits. Attackers leveraging this flaw would likely employ exploitation methods consistent with T1068: Exploitation for Privilege Escalation, aiming to transition from a low-privileged user context to SYSTEM or administrative privileges. The exploit chain typically involves identifying the specific function within the WIA service that processes untrusted input, injecting the malicious format string payload, and triggering the vulnerability through normal application interactions with imaging devices or related APIs. Once executed, the attacker can manipulate stack memory to redirect control flow, leading to code execution in a high-integrity context. This capability undermines the principle of least privilege and compromises the overall security posture of the host system, potentially allowing for further lateral movement within a network environment if the elevated privileges are used to access sensitive resources or deploy additional malware.
Mitigation strategies for this vulnerability primarily involve applying the latest cumulative updates provided by Microsoft, which include patches that correct the input validation logic within the Windows Image Acquisition service. Organizations should prioritize patching systems where WIA is enabled and actively used, although a blanket update approach is recommended to ensure comprehensive protection across all endpoints. In environments where immediate patching is not feasible due to operational constraints, network segmentation can help limit exposure by restricting access to imaging devices from untrusted networks or users. Additionally, disabling the Windows Image Acquisition service on systems that do not require it for peripheral device connectivity reduces the attack surface significantly. Security monitoring tools should be configured to detect anomalous behavior associated with format string exploitation attempts, such as unusual memory access patterns or unexpected privilege changes within WIA-related processes. Regular vulnerability assessments and penetration testing can also help identify instances where legacy services like WIA remain unpatched or misconfigured, ensuring that the organization maintains a robust defense against known exploit vectors targeting system components.