# RUSTSEC-2025-0143 - Unsound APIs of public `constant::Reader` and `StructSchema`

Source: https://junglewise.ai/threats/rustsec-2025-0143-unsound-apis-of-public-constant-reader-and-2b64583d  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2025-12-24  
License: CC BY 4.0 with a link back

Severity: info · Published 2025-12-24

Unsound APIs of public `constant::Reader` and `StructSchema`

Technologies: [capnp (crates.io)](https://junglewise.ai/threats/technologies/capnp). Vendors: [crates.io](https://junglewise.ai/threats/vendors/crates-io).

## Quick answers

**Is This vulnerability exploited in the wild?** No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.

**How severe is This vulnerability?** Informational severity, published 24 December 2025.

**Which products and versions are affected?** capnp (crates.io) SEMVER:introduced=0.0.0-0,fixed=0.24.0.

**Is there a fix for This vulnerability?** Yes. capnp (crates.io): upgrade to 0.24.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**Am I affected?** Check whether you run capnp (crates.io) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- capnp (crates.io): upgrade to 0.24.0 or later

  ```sh
  cargo update -p capnp
  ```


## Affected products

- capnp (crates.io) SEMVER:introduced=0.0.0-0,fixed=0.24.0

## Related threats

- [Cap'n Proto has Undefined Behavior in constant::Reader and StructSchema](https://junglewise.ai/threats/cap-n-proto-has-undefined-behavior-in-constant-reader-and-structschema-455b901b)
- [RUSTSEC-2022-0068 - out-of-bounds read possible when setting list-of-pointers](https://junglewise.ai/threats/cve-2022-46149-cap-n-proto-and-its-rust-implementation-vulnerable-to-out-of)