A directory traversal vulnerability has been found in H2O. Users are advised to update immediately.
EDIT. I am sorry to have included an information leakage vulnerability in my software. Information leakage vulnerability consists of two categories: file leakage and memory leakage. Today we have fixed the former; there are no known vulnerabilities that need to be fixed.
However, considering the fact that it is hard to prove that there is no memory leakage vulnerability, we are going to implement privilege separation for handling TLS private keys in the upcoming 1.5 release just in case so that the private keys would not get exposed even if such vulnerability exist.