RUSTSEC-2026-0204: Invalid pointer dereference in `fmt::Pointer` impl for `Atomic` and `Shared` when the underlying pointer is invalid

> Invalid pointer dereference in `fmt::Pointer` impl for `Atomic` and `Shared` when the underlying pointer is invalid

| Details | |
| ------------------- | ---------------------------------------------- |
| Package | `crossbeam-epoch` |
| Version | `0.9.18` |
| URL | [https://github.com/crossbeam-rs/crossbeam/pull/1276](https://github.com/crossbeam-rs/crossbeam/pull/1276) |
| Date | 2026-07-06 |
| Patched versions | `>=0.9.20` |
| Unaffected versions | `<0.9.0` |

Affected versions of `fmt::Display` dereference the underlying pointer. This causes a invalid pointer dereference e.g., when a pointer created with `Atomic::null` or `Shared::null`. `fmt::Debug` impls and pre-0.9 `fmt::Display` impls, which do not dereference pointers, are not affected by this issue.

See [advisory page](https://rustsec.org/advisories/RUSTSEC-2026-0204.html) for additional details.

Start by reading the linked RustSec advisory and checking where crossbeam-epoch 0.9.18 is declared or resolved in the repository. Confirm whether the dependency can use patched version 0.9.20 or later, then verify the updated dependency resolution with the repository's existing checks; done means the affected version is no longer selected.

Written by the indexing model from the issue text.