CVE-2024-50076 in Linux
Summary
by MITRE • 10/29/2024
In the Linux kernel, the following vulnerability has been resolved:
vt: prevent kernel-infoleak in con_font_get()
font.data may not initialize all memory spaces depending on the implementation of vc->vc_sw->con_font_get. This may cause info-leak, so to prevent this, it is safest to modify it to initialize the allocated memory space to 0, and it generally does not affect the overall performance of the system.
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Analysis
by VulDB Data Team • 08/21/2025
The vulnerability CVE-2024-50076 resides within the Linux kernel's virtual terminal subsystem, specifically in the vt module's con_font_get() function. This issue represents a information disclosure vulnerability that occurs when handling font data within the console terminal interface. The flaw manifests during the retrieval of console font information where the font.data buffer may not be fully initialized with zero values, potentially exposing sensitive kernel memory contents to unprivileged users. The vulnerability is particularly concerning because it operates at the kernel level and affects the virtual console subsystem that provides text-based terminal interfaces for system administration and user interaction.
The technical root cause of this vulnerability stems from improper memory initialization within the console font handling mechanism. When the vc->vc_sw->con_font_get function is invoked to retrieve font data, the allocated memory space for font.data may contain residual kernel data from previous operations or memory allocations. This occurs because the implementation does not guarantee that all memory locations within the allocated buffer are explicitly cleared before being populated with font information. The uninitialized memory regions can contain remnants of sensitive kernel structures, stack data, or other confidential information that should not be accessible to user-space applications. This type of vulnerability falls under the CWE-119 category of "Improper Access to Memory Locations" and represents a classic information disclosure flaw that can be exploited to gain insights into kernel memory layout and potentially aid in more sophisticated attacks.
The operational impact of CVE-2024-50076 extends beyond simple information leakage, as it creates potential attack vectors for privilege escalation and system reconnaissance. An attacker with access to a terminal session could potentially exploit this vulnerability to extract kernel memory contents, which might reveal sensitive information about kernel data structures, memory layouts, or even contain credentials or cryptographic keys that were previously stored in memory. The vulnerability affects systems running Linux kernels that implement the virtual console subsystem and could be particularly dangerous in environments where multiple users share terminal sessions or where kernel memory analysis is performed. The performance impact of the proposed fix is minimal since initializing memory to zero is a simple operation that does not significantly affect system responsiveness or resource utilization. According to ATT&CK framework, this vulnerability aligns with T1005 "Data from Local System" and T1059 "Command and Scripting Interpreter" as it enables information gathering and could facilitate further exploitation attempts.
The recommended mitigation strategy involves implementing explicit memory initialization within the con_font_get() function to ensure that all allocated memory spaces are zeroed before font data is populated. This approach follows secure coding practices by guaranteeing that no residual kernel data remains in memory buffers, thereby preventing information leakage. The fix should be applied across all affected Linux kernel versions and distributions, with priority given to systems handling sensitive operations or those with multiple concurrent users. System administrators should ensure that all kernel updates are applied promptly, as this vulnerability could potentially be leveraged in combination with other exploits to achieve more significant system compromise. The solution maintains backward compatibility while addressing the core memory initialization issue, making it suitable for deployment in production environments without introducing significant operational risks or performance degradation.