Add advisory for bcrypt panic regression (CVE candidate)

crates/bcrypt/RUSTSEC-0000-0000.md

@@ -0,0 +1,74 @@
+```toml
+[advisory]
+id = "RUSTSEC-0000-0000"
+package = "bcrypt"
+date = "2026-06-20"
+url = "https://github.com/Keats/rust-bcrypt/pull/103"
+references = [
+    "https://github.com/Keats/rust-bcrypt/issues/62",
+    "https://github.com/Keats/rust-bcrypt/pull/95",
+    "https://github.com/Keats/rust-bcrypt/commit/f5f1ee2862c1198a85afe3c2f8cd80835162b7e9",
+]
+categories = ["denial-of-service"]
+cvss = "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"
+keywords = ["panic", "utf-8", "denial-of-service"]
+
+[versions]
+patched = [">= 0.19.2"]
+unaffected = ["< 0.19.0"]
+```
+
+# Panic in `bcrypt::verify` on non-ASCII hash input
+
+`bcrypt::verify(password, hash)` and `HashParts::from_str(hash)` panic in
+`str::slice_error_fail` when given a 60-byte `&str` containing a multi-byte
+UTF-8 character at certain byte positions.
+
+## Impact
+
+Any Rust code that calls `bcrypt::verify` (or `HashParts::from_str`) with an
+attacker-controlled hash string will panic. The `bcrypt` crate is
+`#![forbid(unsafe_code)]`, so this is limited to a denial-of-service and
+cannot lead to memory corruption.
+
+Realistic attack contexts include:
+
+- Rust authentication services reading hashes from a database that was
+  previously compromised via, e.g., SQL injection. The attacker can then
+  crash the service on every login attempt against the tampered account.
+- CLI tools accepting hashes from stdin or command-line arguments.
+- Password managers or vault services loading hashes from untrusted
+  configuration sources.
+
+## Root cause
+
+`split_hash` performed five `&str` slicing operations on the input hash:
+`&hash[1..3]`, `&hash[4..6]`, `&hash[7..]`, `&salt_and_hash[..22]`, and
+`&salt_and_hash[22..]`. None of these were char-boundary-checked. Any input
+where a multi-byte UTF-8 character spanned one of those byte positions
+caused a panic.
+
+This is a regression of the fix originally shipped in 2021 for issue #62
+(commit `0833509`). The regression was introduced in the parser rewrite in
+PR #95 (commit `e9a8394`, released as 0.19.0).
+
+The pre-existing regression test `does_no_error_on_char_boundary_splitting`
+was not removed, but was silently rendered ineffective by the new
+`bytes[0] != b'$'` guard, which rejected its input earlier and prevented
+it from reaching the buggy slices — leaving CI green through the regression.
+
+## Fix
+
+`split_hash` now rejects any hash string containing non-ASCII bytes up
+front. A valid bcrypt hash is always exactly 60 ASCII bytes, so this
+closes the entire class of byte-boundary panics rather than guarding each
+slice individually.
+
+The fix was merged in PR #103 and released as `bcrypt 0.19.2` on 2026-06-20.
+
+## Downstream impact
+
+`pyca/bcrypt` (which depended on `bcrypt 0.19.1`) is **not** affected. Its
+Python-side wrapper performs its own byte-level salt parsing before
+invoking `bcrypt::hash_with_salt`, and never reaches the buggy code path
+in `split_hash` or `verify`.