Beginning in October of 2021 both the Vuln and CPE APIs will limit date ranges to 120 days total. In addition, when using a start or end date for the optional parameters both the start and the end date must be provided. Impacts are as follows:
Vuln API:
modStartDate / modEndDate: Both values will now be required when used. Maximum date ranges between dates cannot exceed 120 days.
pubStartDate / pubEndDate: Both values will now be required when used. Maximum date ranges between dates cannot exceed 120 days.
CPE API:
modStartDate / modEndDate: Both values will now be required when used. Maximum date ranges between dates cannot exceed 120 days.
V/r,
The National Vulnerability Database Team