---
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'
---

## Overview

Several 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.

## Impact

- **CWE-415 (Double Free):** the same allocation is freed twice.
- **CWE-416 (Use-After-Free):** a freed allocation is accessed during a repeated `Drop`.

Reachable entirely from safe Rust via `catch_unwind` with element types whose `Drop` can panic.

## Fix

Fixed in `circular-buffer` 2.0.1 by adjusting the buffer's start/end metadata before the elements are dropped.

## Affected packages

- `circular-buffer >= 0.0.0-0, < 2.0.1`

## Remediation

Upgrade to a patched release:

- `circular-buffer 2.0.1`