CVE-2026-93541 in LibXi
Summary
by MITRE • 09/24/2026
An out-of-bounds read in libXi's XQueryDeviceState() in libXi before 1.8.4 could be used by a
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Analysis
by VulDB Data Team • 09/24/2026
The vulnerability identified involves an out-of-bounds read condition within the X Query Device State function of the libXi library, specifically affecting versions prior to 1.8.4. This component is responsible for querying and returning information about input devices connected to an X Window System display server. The flaw arises when the application fails to properly validate the length or bounds of data structures before accessing memory locations associated with device state information. Consequently, if a malicious actor can trigger this function with crafted inputs that exceed expected boundaries, they may cause the program to read from memory regions outside its intended allocation. This type of error is classified under CWE-125, which denotes an out-of-bounds read vulnerability where software reads data past the end or before the beginning of the intended buffer.
From a technical perspective, libXi serves as a client-side library for the X Input Extension protocol, facilitating communication between applications and the display server regarding input devices such as mice, keyboards, and touchscreens. When an application requests device state information, it passes arguments to the underlying C functions in libXi. If these arguments are not rigorously checked against valid ranges or if internal pointer arithmetic is miscalculated due to integer overflow or logic errors, the resulting memory access can retrieve sensitive data from adjacent heap or stack segments. Although out-of-bounds reads typically result in information disclosure rather than immediate code execution, they provide attackers with a mechanism to leak private memory contents. This could include cryptographic keys, session tokens, or other confidential data residing near the queried buffer in memory layout.
The operational impact of this vulnerability is primarily centered on confidentiality and potential stability issues depending on how the leaked data is handled by the consuming application. An attacker who can interact with a vulnerable X11 client might exploit this flaw to perform side-channel attacks or gather intelligence about the system's internal state. In some scenarios, if the read operation triggers an exception that crashes the process without proper error handling, it could also lead to denial of service conditions. However, the most significant risk remains the unauthorized disclosure of memory contents which can be leveraged in subsequent attack chains. This aligns with ATT&CK technique T1082, System Information Discovery, where adversaries gather information about the target environment through local probing or exploitation of software flaws.
Mitigation strategies for this vulnerability involve upgrading libXi to version 1.8.4 or later, which includes patches that enforce strict bounds checking on all device state queries. Developers integrating libXi into their applications should ensure they are linking against patched libraries and consider implementing additional runtime checks if maintaining older versions is unavoidable due to legacy constraints. Furthermore, employing memory-safe programming practices such as using static analysis tools during development can help identify similar boundary errors before deployment. System administrators should monitor for updates from distribution vendors who have backported these fixes to their respective package repositories. Regular patch management and vulnerability scanning remain critical defenses against exploitation of known library flaws in graphical subsystems.