Yes, there's a risk, but it's not significantly higher than having most other home appliances turned on (eg, a lamp, dehumidifier, dish washer or dryer).
Although it heats up, a full-sized oven is insulated, and you're not operating at a very high temperature. Provided it seals well, even if there's a fire, there would be little oxygen to sustain it. I would not trust a toaster oven or desktop oven. with this sort of thing, as they're not as well insulated, nor do they tend to seal well.
As ovens are based on temperature, and will cycle on an off, rather than just feed in a constant amount of power (such as a cook top) ... so it won't get so hot that it causes other issues.