CVE-2026-74673

A flaw was found in the Linux kernel's evdev component. This vulnerability occurs because certain data structures, specifically input_event, are not fully cleared before being sent to user applications. This can result in uninitialized memory from the kernel's internal stack being exposed to an attacker. Such an information leak could potentially reveal sensitive data, compromising system security.

A moderate-severity information leak flaw was found in the Linux kernel's evdev (input event) subsystem. In evdev_pass_values(), and in the related __evdev_queue_syn_dropped() and __pass_event() paths, the struct input_event is allocated on the kernel stack and populated field-by-field without being fully initialized. On architectures where struct input_event contains explicit or implicit padding (for example, the 32-bit __pad field on SPARC64), these uninitialized padding bytes are passed to the client buffer and copied to userspace when input events are read, allowing a local attacker with access to an evdev device node to disclose small fragments of kernel stack memory. The flaw affects confidentiality only, with no direct integrity or availability impact. The Red Hat Enterprise Linux kernel and kernel-rt packages across the affected update streams, and the Red Hat In-Vehicle OS kernel packages, are listed as affected, while the RHEL 6 ELS kernel is out of support scope. Because this is a local-only information disclosure limited to uninitialized padding bytes on architectures where struct input_event is padded, the fix has been deferred for the affected streams and will be delivered in a future kernel update; the residual risk is that a local attacker with access to an input device could obtain small fragments of kernel stack memory.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.