Just weeks ago, Canon confirmed that their latest 5D Mark III DSLR did have a light leak issue, where illumination from the LCD panel in dark environments could disrupt the AE sensor's detection of light.
Canon has swiftly offered free inspection to owners and have also adopted a fix on their newly manufactured 5D Mark III units. To see how Canon rectified this problem, LensRentals.com, who got its first shipment of post-fix 5D Mark IIIs, opened up a unit to take a peek into its internals.
The fix was a simple one, consisting of just black tape, which is pinned to the side of the display.
Source: The Verge