Reported

April 24, 2026

Issued

May 13, 2026

Package

diesel (crates.io)

Type

INFO Unsound

References

• https://github.com/diesel-rs/diesel/pull/5042

Patched

• >=2.3.8

Affected Functions

Version

diesel::debug_query

• <2.3.8

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.

Advisory available under CC0-1.0 license.