Bug 2507252 (CVE-2026-64366)

Summary: CVE-2026-64366 kernel: HID: wacom: fix slab-out-of-bounds write in wacom_wac_queue_insert
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: high    
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 Wacom Human Interface Device (HID) driver. This vulnerability occurs in the `wacom_wac_queue_insert` function when handling incoming reports. Improper management of the kernel's internal buffer (kfifo) can lead to a slab-out-of-bounds write, allowing an attacker to corrupt memory. This memory corruption could potentially result in a denial of service or, in some cases, arbitrary code execution.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-07-25 10:12:55 UTC
In the Linux kernel, the following vulnerability has been resolved:

HID: wacom: fix slab-out-of-bounds write in wacom_wac_queue_insert

wacom_wac_queue_insert() calls kfifo_skip() in a loop when the kfifo
doesn't have enough space for the incoming report. If the kfifo is
empty, kfifo_skip() reads stale data left in the kmalloc'd buffer
via __kfifo_peek_n() and interprets it as a record length, advancing
fifo->out by that garbage value. This corrupts the internal kfifo
state, causing kfifo_unused() to return a value much larger than the
actual buffer size, which bypasses __kfifo_in_r()'s guard:

  if (len + recsize > kfifo_unused(fifo))
      return 0;

kfifo_copy_in() then performs an out-of-bounds memcpy, writing up to
3842 bytes past the 256-byte buffer.

Add a !kfifo_is_empty() condition to the while loop so kfifo_skip()
is never called on an empty fifo, and check the return value of
kfifo_in() to reject reports that are too large for the fifo.