# RUSTSEC-2026-0123: Out-of-bounds read in `bytes_helper` public safe functions

> Attackers can trigger undefined behavior and potential crashes or code execution by calling unsafe public functions with invalid slice positions.

- **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:** 2 May 2026

## What is RUSTSEC-2026-0123?

RUSTSEC-2026-0123 is a memory corruption vulnerability in rustdx, published on 2 May 2026. 

### Official description

The `bytes_helper` module contains multiple public functions
(`into_arr4()`, `into_arr2()`, `u8_from_le_bytes()`) that use
`slice.get_unchecked(pos..pos + N)` without verifying that
`pos + N <= slice.len()`. These are public safe API functions, allowing any
caller to trigger undefined behavior by passing invalid positions.

For example, calling `into_arr4(&data, 10)` where `data` is a 3-byte slice
causes an out-of-bounds access since position 10 exceeds the slice length.

## Which versions are affected by RUSTSEC-2026-0123?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `rustdx` | crates.io | From 0.0.0-0 | 0.4.4 |

## How do I fix RUSTSEC-2026-0123?

Upgrade rustdx to 0.4.4 or later.

## Is RUSTSEC-2026-0123 being exploited?

There is no known exploitation of RUSTSEC-2026-0123 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for RUSTSEC-2026-0123 and fix it if it is affected.

What it is: RUSTSEC-2026-0123 is a memory corruption vulnerability in rustdx, published on 2 May 2026. 
Exploitation: There is no known exploitation of RUSTSEC-2026-0123 in the wild and no public exploit code.

Affected packages and fixed versions:
- rustdx (crates.io): affected from 0.0.0-0; fixed in 0.4.4

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-2026-0123/ (Markdown: https://insights.sbomify.com/RUSTSEC-2026-0123/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/RUSTSEC-2026-0123

---
From sbomify Insights: https://insights.sbomify.com/RUSTSEC-2026-0123/
Summaries are generated and may contain mistakes; the official description above is the record.