Advisories for Cargo/Buffa package

The decode_unknown_field function in buffa's protobuf decoder allocated heap memory in proportion to untrusted input (unknown fields in the serialized protobuf) without enforcing an allocation budget. Any message decoded from untrusted input using code generated with preserve_unknown_fields=true (the default) was affected. A small, well-formed payload of nested unknown fields inside a StartGroup could trigger roughly 22× memory amplification (e.g., a 64 MiB input forcing ~1.4 GB of heap allocation), and …

A soundness bug in buffa's OwnedView<V> allowed safe Rust code to trigger a use-after-free. The OwnedView::decode constructor transmuted a borrowed slice to &'static [u8], and the Deref implementation exposed the promoted 'static lifetime on borrowed view fields (such as &'static str and &'static [u8]) to callers. Because these references appeared to be 'static, the borrow checker permitted them to outlive the OwnedView; once the OwnedView was dropped and its backing …