In versions prior 0.11.3 it's possible to make from_slice panic by feeding it certain malformed input. It's never documented that from_slice (and from_bytes which wraps it) can panic, and its' return type (Result<Self, DecodeError>) suggests otherwise.

In practice, from_slice/from_bytes is frequently used in networking code (for example in rust-libp2p) and is being called with unsanitized data from untrusted sources. This can allow attackers to cause DoS by causing an unexpected panic in the network client's code.

The Tungstenite crate through 0.20.0 for Rust allows remote attackers to cause a denial of service (minutes of CPU consumption) via an excessive length of an HTTP header in a client handshake. The length affects both how many times a parse is attempted (e.g., thousands of times) and the average amount of data for each parse attempt (e.g., millions of bytes).