# Hubuum hubuum_client custom transport bypass in Rust library

Source: https://junglewise.ai/threats/hubuum-hubuum-client-custom-transport-bypass-in-rust-library-e2d3c419  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-24. Updated: 2026-07-25  
License: CC BY 4.0 with a link back

Severity: medium · CVSS 6.3 · Published 2026-07-24

A vulnerability in the Hubuum Rust client library allows certain network requests to bypass security controls like proxies or audit logs. This occurs when the library uses its default connection method instead of a developer-configured custom transport for sensitive tasks like logging in or validating tokens. As a result, login credentials or security tokens could be sent over unintended network paths, potentially exposing them to unauthorized monitoring or violating corporate security policies.

Technologies: [hubuum_client (crates.io)](https://junglewise.ai/threats/technologies/hubuum-client). 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?** Medium severity, with a CVSS score of 6.3, published 24 July 2026.

**Which products and versions are affected?** hubuum_client (crates.io) >= 0.3.0, <= 0.6.0.

**Is there a fix for This vulnerability?** A patch was published on 2026-07-23: Version 0.6.1 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is This vulnerability attacked?** It is attacked over the network, in a software library.

**Am I affected?** Check whether you run hubuum_client (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.

## Technical details

A protection mechanism failure (CWE-693) exists in hubuum_client versions 0.3.0 through 0.6.0. When a developer configures a custom transport via ClientBuilder::with_transport, several operations—including password login, bearer-token validation, and health probes—incorrectly default to the internal reqwest client. This bypasses user-defined security boundaries such as proxy enforcement, request signing, and audit logging. An attacker monitoring the network could potentially capture plaintext credentials or bearer tokens sent outside the intended secure transport. The issue is fixed in version 0.6.1, which also disables automatic redirect following as a defense-in-depth measure.

## Affected products

- hubuum hubuum_client >= 0.3.0, <= 0.6.0

## Timeline

- 2026-07-23: disclosed
- 2026-07-23: patched: Version 0.6.1 released
- 2026-07-24: advisory

## References

- [https://github.com/hubuum/hubuum-client-rust/security/advisories/GHSA-qqc3-94qv-7fw3](https://github.com/hubuum/hubuum-client-rust/security/advisories/GHSA-qqc3-94qv-7fw3)
- [https://github.com/hubuum/hubuum-client-rust/commit/5a5c275ffa45f342459b7d3e977926da643bde50](https://github.com/hubuum/hubuum-client-rust/commit/5a5c275ffa45f342459b7d3e977926da643bde50)
- [https://github.com/hubuum/hubuum-client-rust/releases/tag/v0.6.1](https://github.com/hubuum/hubuum-client-rust/releases/tag/v0.6.1)
- [https://api.github.com/repos/hubuum/hubuum-client-rust/security-advisories/GHSA-qqc3-94qv-7fw3](https://api.github.com/repos/hubuum/hubuum-client-rust/security-advisories/GHSA-qqc3-94qv-7fw3)

## Related threats

- [Hubuum hubuum_client sensitive information disclosure in diagnostics](https://junglewise.ai/threats/hubuum-hubuum-client-sensitive-information-disclosure-in-diagnostics-64d85e10)
- [Hubuum hubuum_client sensitive information leak via redirects](https://junglewise.ai/threats/hubuum-hubuum-client-sensitive-information-leak-via-redirects-d0c7c1e6)