{"id":"RUSTSEC-2026-0256","title":"Panic-safety unsoundness in `truncate_back`, `truncate_front`, `clear`, and `extend_from_slice` (use-after-free / double-free)","summary":"Panic-safety unsoundness in `truncate_back`, `truncate_front`, `clear`, and `extend_from_slice` (use-after-free / double-free)","severity":"none","vendor":"circular-buffer","product":"circular-buffer","ecosystem":"rust","affected":["circular-buffer >= 0.0.0-0, < 2.0.1"],"patched":["circular-buffer 2.0.1"],"published":"2026-08-11","updated":"2026-08-12","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/RUSTSEC-2026-0256","references":[{"url":"https://crates.io/crates/circular-buffer"},{"url":"https://rustsec.org/advisories/RUSTSEC-2026-0256.html"},{"url":"https://github.com/andreacorbellini/rust-circular-buffer/blob/master/CHANGELOG.md"}],"tags":["osv","rust"],"ingestedAt":"2026-08-12T19:18:09.006Z","slug":"RUSTSEC-2026-0256","body":"## Overview\n\nSeveral methods in `circular-buffer` drop elements before updating the buffer's start/end metadata. If an element's `Drop` panics during the drop, the metadata update is skipped, so the buffer still treats the already-dropped elements as live. When the buffer is later dropped (or used after the panic is caught), those elements are visited again — a use-after-free / double-free reachable from safe Rust.\n\n## Impact\n\n- **CWE-415 (Double Free):** the same allocation is freed twice.\n- **CWE-416 (Use-After-Free):** a freed allocation is accessed during a repeated `Drop`.\n\nReachable entirely from safe Rust via `catch_unwind` with element types whose `Drop` can panic.\n\n## Fix\n\nFixed in `circular-buffer` 2.0.1 by adjusting the buffer's start/end metadata before the elements are dropped.\n\n## Affected packages\n\n- `circular-buffer >= 0.0.0-0, < 2.0.1`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `circular-buffer 2.0.1`","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}