Mummies are widely considered to be one of the most iconic undead monsters, but are often overshadowed by their vampire & zombie brethren.
Furthermore, while the vampire has a bevy of supernatural abilities aside from their bloodsucking repertoire, and zombies can eat the brains of living creatures to make more of their own via biological pathogens or magick hexes, the mummy has never been able to compete against them what with their fragility (desiccation, flammability, heat/cold weakness) without the aid of some vague 'magick'. One can't help but feel that the mummies' quantifiable existence & reproduction in reality has more or less come to encompass their 'curse' in this regard.
The only example of "mummy danger" that didn't come from vengeful spirits or magick (e.g., The Mummy franchise) I know of is:
El Dorado in Uncharted: Drake's Fortune where the sarcophagus its mummy is sealed in contained an extremely-infectious, immediately-debilitating virus presumably infecting the mummy.
While this works on its own, I feel it only doubles-down on the supremacy of the zombie camp.
Various cultures throughout history have used various materials (Egyptian papyri/linen wrappings, Han dynasty jade suits, layers of heavy cloth of the Incas or other Andean peoples) to insulate the body from natural phenomena which could exacerbate decay. Whereas others have specific methods (Inca refrigeration, Kabayan fire mummies) to the same ends. Moreover, an extra step of preservation - post-embalming or not - is established by encasing the body in a storage medium (Egyptian sarcophagi, Chachapoyas purunmachu) with a hermetic seal or vacuum even provided in some circumstances (Rosalia Lombardo, Vladimir Lenin, incorruptible saints).
If we humans have used embalming & preservation on our dead since antiquity - if not for the veneration of the specific dead and/or the comfort of their admired - then what exactly is the practicality of separating our dead from our living with as many 'layers' as necessary? If a vampire would start drinking human/animal/medical blood (and creating more vampires) if one went loose today, what could a mummy do to pose an active danger to the living & society if let loose today? How & why? The best reason(s) for the unique threat of the mummy don't require any specific materials, methods, or climates to work - use as many of them as you want! The best answer shouldn't require viral or magick agents as a requirement of the danger.