vproxy is an HTTP/HTTPS/SOCKS5 proxy server. In versions 2.3.3 and below, untrusted data is extracted from the user-controlled HTTP Proxy-Authorization header and passed to Extension::try_from and flows into parse_ttl_extension where it is parsed as a TTL value. If an attacker supplies a TTL of zero (e.g. by using a username such as configuredUser-ttl-0), the modulo operation timestamp % ttl will cause a division by zero panic, causing the server to crash causing a denial-of-service. This is fixed in version 2.4.0.
The product divides a value by zero.