Sandstorm Cap'n Proto before 0.4.1.1 and 0.5.x before 0.5.1.2, when an application invokes the totalSize method on an object reader, allows remote peers to cause a denial of service (CPU consumption) via a crafted small message, which triggers a "tight" for loop.  NOTE: this vulnerability exists because of an incomplete fix for CVE-2015-2312.