# CVE-2026-101059: utcp-http OAuth2 tokenUrl validation bypass in OpenAPI conversion

Source: https://junglewise.ai/threats/cve-2026-101059-utcp-http-before-1-1-4-fails-to-validate-the-oauth2-tokenurl  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-27. Updated: 2026-09-27  
License: CC BY 4.0 with a link back

CVE-2026-101059 · Severity: high · CVSS 7.1 · Published 2026-09-27

utcp-http is a library that automatically generates tools from remote OpenAPI specifications to call APIs with OAuth2 authentication. The library fails to validate the OAuth2 token endpoint URL provided in the API specification, allowing an attacker who controls a malicious specification to intercept and steal the victim's OAuth2 credentials (client_id and client_secret). An attacker can redirect credential submissions to their own server or internal services, enabling credential theft or internal network attacks.

Vendors: [Universal Tool Calling Protocol](https://junglewise.ai/threats/vendors/universal-tool-calling-protocol).

## Quick answers

**Is CVE-2026-101059 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-101059 being exploited in the wild.

**How severe is CVE-2026-101059?** High severity, with a CVSS score of 7.1, published 27 September 2026.

**Which products and versions are affected?** Universal Tool Calling Protocol Utcp-Http before 1.1.4.

**Is there a fix for CVE-2026-101059?** A patch was published on 2026-06-14: Version 1.1.4 released with fix Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-101059 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-101059?** Check whether you run Universal Tool Calling Protocol Utcp-Http 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

The vulnerability is a trust boundary bypass in OpenAPI conversion where the OAuth2 tokenUrl field is extracted directly from untrusted remote specifications without validation. While discovery URLs and tool invocation URLs are protected by the ensure_secure_url() function (which blocks non-HTTPS non-loopback URLs and internal address ranges), the tokenUrl field bypasses this check entirely. When a victim calls an OAuth2-protected tool, session.post(auth_details.token_url, data=body_data) sends credentials to the unvalidated endpoint, enabling credential theft or server-side request forgery.

## Affected products

- universal-tool-calling-protocol utcp-http before 1.1.4

## Timeline

- 2026-09-27: disclosed: CVE-2026-101059 published
- 2026-06-14: patched: Version 1.1.4 released with fix

## References

- [https://github.com/universal-tool-calling-protocol/python-utcp/security/advisories/GHSA-8cp3-qxj6-px34](https://github.com/universal-tool-calling-protocol/python-utcp/security/advisories/GHSA-8cp3-qxj6-px34)
- [https://www.vulncheck.com/advisories/utcp-http-before-1.1.4-oauth2-tokenurl-trust-boundary-bypass](https://www.vulncheck.com/advisories/utcp-http-before-1.1.4-oauth2-tokenurl-trust-boundary-bypass)