UnsoundRUSTSEC-2026-0134 · diesel
RUSTSEC-2026-0134: Unsound access to padding bytes while serializing date/time values using the Mysql backend
Short answerdiesel has an API that can cause undefined behaviour from safe code: Unsound access to padding bytes while serializing date/time values using the Mysql backend. Fixed in 2.3.8.
| Crate | diesel |
|---|---|
| Type | Unsound |
| Affected versions | Before 2.3.8. |
| Fixed in | 2.3.8 |
| Severity | not scored |
| Published | 2026-04-24 |
| Last changed | 2026-05-13 |
| Also known as | none |
| Affected functions | diesel::serialize::ToSql<Date,Mysql>, diesel::serialize::ToSql<DateTime,Mysql>, diesel::serialize::ToSql<Time,Mysql>, diesel::serialize::ToSql<Timestamp,Mysql> |
What to do
- See which version you have:
cargo tree -i diesel(it also shows which of your dependencies pulls it in). - Update within your version requirement:
cargo update -p diesel. If the fix is a newer major or minor than your requirement allows, raise it in Cargo.toml (for examplediesel = "2.3.8") or update the dependency that pulls it in. - Check again with
cargo audit, or paste your Cargo.lock into our Cargo.toml checker.
Details from the advisory
Diesel relies on libmysqlclient for interacting with Mysql compatible databases. This library requires to provide date/time values according to the byte layout of their MYSQL_TIME type.
Diesel replicated this type as #[repr(C)] struct, populated all the fields of this struct and then casted this value to an array of bytes. As this cast exposes padding bytes contained in this struct, this is undefined behaviour.
This vulnerability affects any user serializing date/time values using the Mysql 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 manually serializes the relevant data without accessing the padding bytes.
References
- Package: crates.io/crates/diesel
- Advisory: rustsec.org/advisories/RUSTSEC-2026-0134.html
- Web: github.com/diesel-rs/diesel/pull/5042
From the RustSec Advisory Database (CC0-1.0) via the OSV export, downloaded Oct 24, 2026. Severity score computed from the published CVSS vector.
Other advisories for diesel
- Vulnerability CriticalRUSTSEC-2021-0037 · 2021-03-05Fix a use-after-free bug in diesels Sqlite backend
- VulnerabilityRUSTSEC-2024-0365 · 2024-08-23Binary Protocol Misinterpretation caused by Truncating or Overflowing Casts
- UnsoundRUSTSEC-2026-0111 · 2026-04-24Possible UTF-8 corruption in Diesels SQLite backend
- UnsoundRUSTSEC-2026-0135 · 2026-04-24Unsound transmute while debug/display printing batch Insert statements in Diesel's SQLite backend
- VulnerabilityRUSTSEC-2026-0136 · 2026-04-24Command injection in Diesel's implementation of `COPY FROM`/`COPY TO`
- VulnerabilityRUSTSEC-2026-0137 · 2026-04-24Possible unaligned data access for implementations of `SqliteAggregate`
- UnsoundRUSTSEC-2026-0172 · 2026-06-05Possible use after free when deserializing a SQLite database via `SqliteConnection::deserialize_readonly_database`
Up next
Same cratediesel: security historyEvery advisory for this crate, and whether it is safe to use today.Read it next →Did this answer your question?