# RUSTSEC-2026-0309: `SinglyLinkedList::remove` dereferences a null link

> A null pointer dereference in SinglyLinkedList::remove causes undefined behavior and potential crashes when removing nodes from empty or invalid lists.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Not stated
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 20 Sep 2026

## What is RUSTSEC-2026-0309?

RUSTSEC-2026-0309 is a vulnerability in bun_collections, published on 20 Sep 2026. 

### Official description

In versions before 0.2.1, `SinglyLinkedList::remove` is safe and walks the intrusive list with an unchecked dereference. On an empty list, or when `node` is not in the list, `(*current_elm).next` reads a null pointer. That is undefined behavior. The list head is a raw `*mut Node<T>`, and safe code can construct the empty list.

The maintainer fixed this in 0.2.1 by rejecting those two cases with an unconditional `assert!` before the pointer is followed, matching the upstream Zig `unwrap` on the same paths. 0.2.0 was yanked. Versions 0.1.0 through 0.1.13 are still published and still contain the unchecked walk.

## Which versions are affected by RUSTSEC-2026-0309?

1 open source package ship an affected version, including bun_collections.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `bun_collections` | crates.io | From 0.0.0-0 | 0.2.1 |

## How do I fix RUSTSEC-2026-0309?

Upgrade bun_collections to 0.2.1 or later.

## Is RUSTSEC-2026-0309 being exploited?

There is no known exploitation of RUSTSEC-2026-0309 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for RUSTSEC-2026-0309 and fix it if it is affected.

What it is: RUSTSEC-2026-0309 is a vulnerability in bun_collections, published on 20 Sep 2026. 
Exploitation: There is no known exploitation of RUSTSEC-2026-0309 in the wild and no public exploit code.

Affected packages and fixed versions:
- bun_collections (crates.io): affected from 0.0.0-0; fixed in 0.2.1

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/RUSTSEC-2026-0309/ (Markdown: https://insights.sbomify.com/RUSTSEC-2026-0309/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/RUSTSEC-2026-0309

---
From sbomify Insights: https://insights.sbomify.com/RUSTSEC-2026-0309/
Summaries are generated and may contain mistakes; the official description above is the record.