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Add advisory for potato: invalid UTF-8 from safe code via RefStr #2854

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Add advisory for potato: invalid UTF-8 from safe code via RefStr #2854

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27 changes: 27 additions & 0 deletions crates/potato/RUSTSEC-0000-0000.md
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```toml
[advisory]
id = "RUSTSEC-0000-0000"
package = "potato"
date = "2026-05-02"
url = "https://github.com/fawdlstty/potato/issues/1"
informational = "unsound"
categories = ["memory-corruption"]
keywords = ["undefined-behavior", "utf-8"]

[versions]
patched = []
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@djc djc May 13, 2026

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It looks like a fix has been released for this issue.

```

# `RefStr::from_slice()` allows constructing invalid UTF-8 from safe code

`RefStr::from_slice(data, start, len)` is declared safe but uses
`unsafe { data.get_unchecked(start) }` internally without validating `start`
and `len`. Callers can construct a `RefStr` pointing to arbitrary bytes.

Combined with `to_str()`, which calls `std::str::from_utf8_unchecked()` on
the underlying bytes, a caller can produce an invalid `&str` that violates
Rust's safety requirements. For example, slicing a multi-byte UTF-8 character
in the middle produces an invalid `&str`.

Both `from_slice()` and `to_str()` are public safe APIs, so this undefined
behavior can be triggered without writing any `unsafe` code.