Add advisory for gix-date vulnerability

Author: shinmao

crates/gix-date/RUSTSEC-0000-0000.md

@@ -0,0 +1,21 @@
+```toml
+[advisory]
+id = "RUSTSEC-0000-0000"
+package = "gix-date"
+date = "2025-12-29"
+url = "https://github.com/GitoxideLabs/gitoxide/issues/2305"
+categories = ["memory-corruption"]
+keywords = ["utf8", "undefined-behavior"]
+
+[affected.functions]
+"gix_date::parse::TimeBuf::as_str" = ["<= 0.11.1"]
+
+[versions]
+patched = [">= 0.12.0"]
+```
+
+# Non-utf8 String can be created with `TimeBuf::as_str`
+
+The function `gix_date::parse::TimeBuf::as_str` can create an illegal string containing non-utf8 characters. This violates the safety invariant of `TimeBuf` and can lead to undefined behavior when consuming the string.
+
+The bug can be prevented by adding `str::from_utf8` to the function `TimeBuf::write`.