This indicates an attack attempt to exploit a Denial of Service Vulnerability in Cesanta Mongoose.
The vulnerability is due to improper handling of objects in memory, potentially leading to an infinite loop. A remote, unauthenticated attacker could exploit the vulnerability by sending crafted requests to a targeted system. Successful exploitation of the vulnerability could cause denial-of-service conditions.
Cesanta Mongoose 6.16
Denial of Service: Remote attackers can crash vulnerable systems.
Apply the most recent upgrade or patch from the vendor.