Add advisory for bytes-str: BytesString::split_off can break UTF-8 invariant

crates/bytes-str/RUSTSEC-0000-0000.md

@@ -0,0 +1,68 @@
+```toml
+[advisory]
+id = "RUSTSEC-0000-0000"
+package = "bytes-str"
+date = "2026-03-11"
+url = "https://github.com/dudykr/ddbase/issues/90"
+informational = "unsound"
+categories = ["memory-corruption"]
+keywords = ["soundness", "utf-8", "char-boundary", "invalid-str"]
+
+[versions]
+patched = []
+unaffected = []
+```
+
+# `BytesString::split_off` can break UTF-8 invariants
+
+`BytesString::split_off` does not validate UTF-8 character boundaries, but `BytesString::as_str` uses `from_utf8_unchecked` and assumes the internal buffer remains valid UTF-8. Safe code can construct a valid `BytesString`, split at a non-character boundary, then obtain an invalid `&str` through `as_str`, leading to undefined behavior when the string is iterated. The upstream issue suggests adding character-boundary checks (or panicking) in `split_off` and similar index-based operations.
+
+No patched version is currently available. The issue affects the reported version `0.2.7`.
+
+In addition, the crate appears to be unmaintained. The maintainer has been contacted via this public issue and has not responded for over three months, and the repository shows no visible maintenance activity for roughly eleven months.
+
+## Example
+
+```rust
+use bytes_str::BytesString;
+
+fn main() {
+    // Valid UTF-8 for "é" = [0xC3, 0xA9]
+    let mut s = BytesString::from_utf8_slice(b"\xC3\xA9").unwrap();
+
+    // Split inside a multi-byte code point (safe call)
+    let _ = s.split_off(1);
+
+    // as_str assumes UTF-8 invariant and returns &str
+    let corrupted = s.as_str();
+
+    // This triggers UB under Miri
+    let _ = corrupted.chars().next();
+}
+```
+
+## Miri output
+
+```text
+Corrupted bytes: [195]
+error: Undefined Behavior: entering unreachable code
+  --> /home/yilin/.rustup/toolchains/nightly-2025-12-06-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/str/validations.rs:48:23
+   |
+48 |     let y = unsafe { *bytes.next().unwrap_unchecked() };
+   |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Undefined Behavior occurred here
+   |
+   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
+   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
+   = note: BACKTRACE:
+   = note: inside `core::str::validations::next_code_point::<'_, std::slice::Iter<'_, u8>>` at /home/yilin/.rustup/toolchains/nightly-2025-12-06-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/str/validations.rs:48:23: 48:54
+   = note: inside `<std::str::Chars<'_> as std::iter::Iterator>::next` at /home/yilin/.rustup/toolchains/nightly-2025-12-06-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/str/iter.rs:42:18: 42:49
+note: inside `main`
+  --> src/main.rs:13:46
+   |
+13 | ...ng chars: {:?}", corrupted_str.chars().next());
+   |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
+
+error: aborting due to 1 previous error
+```