mopa is technically unsound

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

not scored

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

The mopa crate redefines the deprecated TraitObject struct from core::raw like so: This is done to then transmute a reference to a trait object (&dyn Trait for any trait Trait) into this struct and retrieve the data field for the purpose of downcasting. This is used to implement downcastrefunchecked(), in terms of which downcastref() is also implemented. Same goes for mutable reference downcasting and Box downcasting. The Rust compiler explicitly reserves the right to change the memory layout of &dyn Trait for any trait Trait. The worst case scenario is that it swaps data and vtable, making an executable location breach and compromisation of ASLR possible, since reads from data would read vtable instead. Likewise, arbitrary code execution is also theoretically possible if reads of vtable generated by the compiler read data instead. While, as of Rust 1.52, this unsound assumption still holds true, updating the compiler may silently create UB in a crate which previously compiled and…

Published by the source

17 Jun 2022, 00:12 UTC

Last modified by the source

13 Jun 2023, 18:35 UTC

Source last checked

26 Oct 2026, 15:34 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-8mv5-7x95-7wcf

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: GHSA-8mv5-7x95-7wcf

Advisory: `mopa` is technically unsound
IDs: GHSA-8mv5-7x95-7wcf
Record: https://patchnext.com/advisories/ghsa-8mv5-7x95-7wcf (revision 1, source checked 26 Oct 2026, 15:34 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Unrated
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io mopa: affected <= 0.2.2

## Suggested inspection (read-only)
- crates.io mopa: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on mopa.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-8mv5-7x95-7wcf (GitHub-reviewed advisory GHSA-8mv5-7x95-7wcf lists affected ranges: crates.io mopa >=0 <=0.2.2)

Commands are suggestions: review each one before running it.