Report privately, not through the public issue tracker:

• Preferred: GitHub's private vulnerability reporting, from the repository's Security tab.
• Alternative: email libraz@libraz.net.

Include what you sent in, what happened, the affected version, and a minimal reproduction if you have one. Expect an acknowledgement within a few days.

Pre-1.0. Fixes land on the latest release only; older versions are not patched.

Suzume tokenizes text it did not produce, and loads a dictionary it is handed, so both inputs are the interesting surface. In scope:

• Text that causes a crash, a hang, unbounded memory growth, or a read or write outside an allocation — in the C++ core or through any of the bindings.
• A crafted dictionary or model file that does the same, or that makes the tokenizer read a file it was not pointed at.
• Anything that escapes the WebAssembly sandbox, or that lets tokenized input reach the network or the filesystem from the browser build.

• Wrong segmentation. A boundary in the wrong place is an accuracy bug; report it as a normal issue.
• Documented limits behaving as documented — input length caps and the like. A limit that can be bypassed is in scope.
• Vulnerabilities in the text being tokenized, or in whatever consumes the tokens afterwards.
• Findings that need an attacker to already control the process or to replace the dictionary file on disk.