# GHSA-4v52-7q2x-v4xj: Parts of Report are dropped as the wrong type during downcast

> Incorrect type handling during error downcasting causes memory corruption or leaks, potentially leading to code execution or crashes in applications using this Rust library.

- **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:** 5 Mar 2024
- **Also known as:** RUSTSEC-2024-0021

## What is GHSA-4v52-7q2x-v4xj?

GHSA-4v52-7q2x-v4xj is a memory corruption vulnerability in eyre, published on 5 Mar 2024. 

### Official description

In affected versions, after a `Report` is constructed using `wrap_err` or
`wrap_err_with` to attach a message of type `D` onto an error of type `E`, then
using `downcast` to recover ownership of either the value of type `D` or the
value of type `E`, one of two things can go wrong:

- If downcasting to `E`, there remains a value of type `D` to be dropped. It is
  incorrectly "dropped" by running `E`'s drop behavior, rather than `D`'s. For
  example if `D` is `&str` and `E` is `std::io::Error`, there would be a call of
  `std::io::Error::drop` in which the reference received by the `Drop` impl does
  not refer to a valid value of type `std::io::Error`, but instead to `&str`.

- If downcasting to `D`, there remains a value of type `E` to be dropped. When
  `D` and `E` do not happen to be the same size, `E`'s drop behavior is
  incorrectly executed in the wrong location. The reference received by the
  `Drop` impl may point left or right of the real `E` value that is meant to be
  getting dropped.

In both cases, when the `Report` contains an error `E` that has nontrivial drop
behavior, the most likely outcome is memory corruption.

When the `Report` contains an error `E` that has trivial drop behavior (for
example a `Utf8Error`) but where `D` has nontrivial drop behavior (such as
`String`), the most likely outcome is that downcasting to `E` would leak `D`.

## Which versions are affected by GHSA-4v52-7q2x-v4xj?

3 open source packages ship an affected version, including eyre.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `eyre` | crates.io | From 0.6.9 | 0.6.12 |
| `eyre` | crates.io | From 0.6.9 | 0.6.12 |
| `eyre` | crates.io | From 0.6.9 | 0.6.12 |

## How do I fix GHSA-4v52-7q2x-v4xj?

Upgrade eyre to 0.6.12 or later.

## Is GHSA-4v52-7q2x-v4xj being exploited?

There is no known exploitation of GHSA-4v52-7q2x-v4xj in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for GHSA-4v52-7q2x-v4xj and fix it if it is affected.

What it is: GHSA-4v52-7q2x-v4xj is a memory corruption vulnerability in eyre, published on 5 Mar 2024. 
Exploitation: There is no known exploitation of GHSA-4v52-7q2x-v4xj in the wild and no public exploit code.

Affected packages and fixed versions:
- eyre (crates.io): affected from 0.6.9; fixed in 0.6.12
- eyre (crates.io): affected from 0.6.9; fixed in 0.6.12
- eyre (crates.io): affected from 0.6.9; fixed in 0.6.12

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/GHSA-4v52-7q2x-v4xj/ (Markdown: https://insights.sbomify.com/GHSA-4v52-7q2x-v4xj/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/GHSA-4v52-7q2x-v4xj

---
From sbomify Insights: https://insights.sbomify.com/GHSA-4v52-7q2x-v4xj/
Summaries are generated and may contain mistakes; the official description above is the record.