# RUSTSEC-2026-0135: Unsound transmute while debug/display printing batch Insert statements in Diesel's SQLite backend

> Unsound transmute in Diesel's SQLite backend during debug printing can cause undefined behavior, potentially leading to crashes or code execution.

- **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:** 24 Apr 2026

## What is RUSTSEC-2026-0135?

RUSTSEC-2026-0135 is a memory corruption vulnerability in diesel, published on 24 Apr 2026. 

### Official description

Diesel allows users to output the generated SQL for any query DSL construct via th `diesel::debug_query` function as `Display` and `Debug` output.

For the particular implementation used by batch Insert statements in the SQLite backend Diesel relied on an unspecified transmute between types with a `#[repr(rust)]` layout. This is formally undefined behaviour as the compiler is free to change the layout of these types at any time. 

This vulnerability affects users that print out batch insert statements constructed using an array/vector of values without default values using `diesel::debug_query` on the SQLite backend.

## Mitigation

The preferred mitigation to the outlined problem is to update to Diesel version 2.3.8 or newer, which includes fixes for the problem.

## Resolution

Diesel now uses a sound cast instead.

## Which versions are affected by RUSTSEC-2026-0135?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `diesel` | crates.io | From 0.0.0-0 | 2.3.8 |

## How do I fix RUSTSEC-2026-0135?

Upgrade diesel to 2.3.8 or later.

## Is RUSTSEC-2026-0135 being exploited?

There is no known exploitation of RUSTSEC-2026-0135 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for RUSTSEC-2026-0135 and fix it if it is affected.

What it is: RUSTSEC-2026-0135 is a memory corruption vulnerability in diesel, published on 24 Apr 2026. 
Exploitation: There is no known exploitation of RUSTSEC-2026-0135 in the wild and no public exploit code.

Affected packages and fixed versions:
- diesel (crates.io): affected from 0.0.0-0; fixed in 2.3.8

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-2026-0135/ (Markdown: https://insights.sbomify.com/RUSTSEC-2026-0135/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/RUSTSEC-2026-0135

---
From sbomify Insights: https://insights.sbomify.com/RUSTSEC-2026-0135/
Summaries are generated and may contain mistakes; the official description above is the record.