Bug 2521381 (CVE-2026-74673)

Summary: CVE-2026-74673 kernel: Input: evdev - fix information leak in evdev_pass_values()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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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.
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Description OSIDB Bzimport 2026-08-22 15:42:44 UTC 
In the Linux kernel, the following vulnerability has been resolved:

Input: evdev - fix information leak in evdev_pass_values()

In evdev_pass_values(), the input_event structure is allocated on the
kernel stack and populated field-by-field. However, it is never fully
initialized. On architectures where struct input_event contains explicit
or implicit padding (such as the 32-bit __pad field on SPARC64), these
padding bytes are left uninitialized.

When this event structure is subsequently passed to the client buffer
and later copied to userspace, the uninitialized padding bytes leak
kernel stack memory, potentially exposing sensitive information.

Similar issues exist in __evdev_queue_syn_dropped and __pass_event.

Fix this by explicitly zeroing the entire event structure with memset()
before populating its fields. This ensures all padding bytes are cleared
before the data crosses the security boundary.
Comment 1 gkamathe 2026-08-24 09:51:03 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026082230-CVE-2026-74673-da72@gregkh/T